Brush type contact material and manufacturing method for the same

Abstract

The present invention relates to a brush type contact material, including one or more curved metal pawls of which ends come into contact with objects to be contacted. The ends of the pawls have an arc-like cross section in a thickness direction, a curvature radius R1 on a front side from a contact point with the object to be contacted and a curvature radius R2 on a back side from the contact point are formed so as to be R1R2, and also both ends in a width direction of the pawl are chamfered. At this time, preferably, R1 is larger than R2 (R1>R2), and R1 divided by R2 (R1/R2) is 3.0 or less. The brush type contact material according to the present invention enables a smoother sliding movement than ever before and can be relatively simply manufactured.

Claims

1. A brush type contact material, comprising one or more curved metal pawls for coming into contact with objects to be contacted, wherein each metal pawl has a contact end having a contact point; wherein a cross section normal to the length of each metal pawl is of substantially constant width and thickness along the length of the metal pawl; wherein each metal pawl is concave on a back side from the contact point and convex on a front side from the contact point; wherein the contact end of each pawl has a curvature in a thickness direction, including a curvature radius R1 on the front side from the contact point and a curvature radius R2 on the back side from the contact point such that the curvatures R1 and R2 are on opposing sides of the contact point; and wherein R1R2, and R1/R2 is 3.0 or less.

2. The brush type contact material according to claim 1, wherein the both ends in a width direction of the pawl are chamfered or round-chamfered within a range of W/10 to W/4 of a brush width W at the both ends.

3. A manufacturing method for a brush type contact material, the contact material defined in claim 1, comprising the steps of: punching a strip material, in which multiple metal pawls are connected, from a thin plate; and forming by polishing the pawl ends by applying a grind stone while holding the strip material in a semi fixed state.

4. The brush type contact material according to claim 1, wherein the contact end is configured such that the contact end will come into contact with a substrate, which is an object to be contacted, at an angle in the range of 70 to 85.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates an appearance of a slider including a general brush type contact material.

(2) FIG. 2 illustrates an appearance of a strip material of a contact piece of a punched sliding material.

(3) FIG. 3 illustrates a cross-sectional shape of a pawl end of the brush type contact material according to the present invention.

(4) FIG. 4 is a diagram illustrating a processing example of both pawl ends of the brush type contact material according to the present invention.

(5) FIG. 5 is a photograph showing a pressed pawl end according to the present embodiment.

(6) FIG. 6 is a photograph showing a pawl end after polishing according to Example 1.

(7) FIG. 7 is a photograph showing a pawl end after polishing according to Example 3.

(8) FIG. 8 is a photograph showing a pawl end after polishing according to Examples 4 to 6.

(9) FIG. 9 is a schematic view of a brush evaluation circuit used in the present embodiment.

(10) FIG. 10 is a diagram illustrating a measurement result of linearity after a durability test according to Example 1.

DESCRIPTION OF EMBODIMENTS

(11) Hereinafter, preferred examples of the present invention will be described. A thin plate material having a width of 23 mm and a thickness of 0.12 mm was prepared by rolling it to the material with a composition of Ag 39.5 wt %, Pd 43.0 wt %, Cu 17.0 wt %, and Pt 0.5 wt %. A strip material 1, in which multiple sliding contact pieces 10 were connected in a belt shape as illustrated in FIG. 2, was obtained by pressing the thin plate material.

(12) Each sliding contact piece 10 has a base 12, two brushes 11 extending from the base 12, and is connected to the adjacent sliding contact pieces 10 in the base 12 via a cutting margin 13. Each brush 11 has three pawls (a width diameter is 0.4 mm) which have the same length and are formed in a comb-tooth shape. Also, in the both brushes 11, pawl ends 11a are arranged in parallel and are arranged on a straight line.

(13) FIG. 5 is a photograph showing a pressed pawl end. A surface of the pawl end 11a in this stage was rough by punching by press. A shape of the end portion was asymmetrically, and an outline of an inwardly pressed end surface was an irregular (indefinite) curved shape. In detail, the end portion includes a shearing (press-sag) surface in an initial punching stage and a fracture (press-burr) surface in a later punching stage.

(14) After pressing, the pawl end was polished. Polishing was performed in a half-fixed state while masking a portion other than the pawl end polishing portion 11a of a punched strip material and holding the cutting margin 13 while providing the cutting margin 13 under a grind stone. The grind stone having a width capable of polishing the multiple pawl end polishing portions 11a at the same time came into contact with and passed through the end polishing portion 11a while rotating and shaking from a vertical direction of the strip material. Also, a holding angle and a feeding speed of the strip material during polishing and a cutting depth and a rotation speed of a grind stone were controlled when a pawl end, of which R1 and R2 on front and back sides are different, was polished. For example, polishing angles of strip materials in Examples 1 to 3 to be described below were set to 45. Also, although polishing angles of strip materials in Examples 4 to 6 were 30 in common, a cutting depth and a rotation speed of a grind stone were changed.

(15) After polishing as described above, a brush type contact material was obtained in which sliding contact points having pawls curved by bending were connected in a belt shape. A shape of a pawl end according to each example will be as follows. R1 and R2 of a pawl end were measured on a center section of a pawl.

(16) TABLE-US-00001 TABLE 1 Sectional shape Chamfering of R1 R2 end portion Example 1 0.08 0.04 30 Example 2 0.06 0.05 15 Example 3 0.06 0.03 R0.3 Example 4 0.06 0.06 45 Example 5 0.045 0.045 R0.2 Example 6 0.03 0.03 30

(17) FIGS. 6 and 7 are photographs showing the pawl 11a ends of the brush type contact materials according to Examples 1 and 3, respectively. A surface of the pawl end of the obtained brush type contact material was smooth. Also, in the sectional photographs, R shapes on the front and back sides are different. The both ends have inclination by chamfering. FIG. 8 is a photograph showing the pawl 11a ends according to Examples 4 to 6. The pawl ends according to these examples had entirely uniform semicylindrical shapes.

(18) Next, a durability test was conducted on a contact material according to each example for evaluation of electrical characteristics. FIG. 9 is a schematic view of a brush evaluation circuit. A brush type contact material is horizontally attached to a substrate having an arc-shaped resistive element so that an output becomes 0V at an angle of 0, and the output becomes 5V at the angle of 90. In the durability test, the brush type contact material was slid for 200 million times on the resistive element illustrated in FIG. 9, and then electrical characteristics (linearity) was measured. In the measurement of linearity, a sensor output voltage (an angle vs. an output voltage from a brush) was measured while changing a brush angle by applying a constant voltage to the resistive element according to FIG. 9 (an angle range of the both ends was excluded since an error becomes large). In the measurement, the linearity was evaluated by setting a displacement between a reference output voltage (logical output) and an output potential from a brush as a change rate %.

(19) FIG. 10 illustrates an example of the linearity measurement results and illustrates the linearity measurement results after the durability in Example 1. Angle-voltage data refers to a left side main scale, and linearity refers to a right side sub scale. FIG. 10 indicates that the linearity according to this example has a range (linearity) of 0.7% with respect to a logical value and has excellent linearity after a durability test. It is said that linearity within 2.0% is required as an in-vehicle component standard to satisfy the regulation of emissions from motor vehicles. Hereinafter this regulation might be tightened, and linearity of 1.5% might be required for further performance upgrade. The contact material according to Example 1 can satisfy the strict standard. Table 2 illustrates the linearity measurement result according to each example.

(20) TABLE-US-00002 TABLE 2 Linearity change rate Example 1 0.7% Example 2 0.8% Example 3 0.9% Example 4 1.1% Example 5 1.2% Example 6 1.6%

(21) Table 2 indicates that all of the brush type contact materials according to Examples 1 to 6 have linearity of 2% or less and have characteristics satisfying the current in-vehicle component standard. Also, it was confirmed that an outstanding characteristics result of 1% or less could be obtained by differing R1 and R2 like Example 1.

INDUSTRIAL APPLICABILITY

(22) As described above, the brush type contact material according to the present invention enables a smoother sliding movement than ever before as a result of considering a pawl end shape in detail. This brush type contact material can be relatively simply manufactured without heating after forming and without changing mechanical properties the configuration material has. The present invention is preferred as a contact material of a slider in a sensor such as a position sensor and a resistor.