JP5568887B2 - Liquid level detector - Google Patents

Description

  The present invention relates to a liquid level detection device, and more particularly to a liquid level detection device in which a sliding contact slides on a fixed electrode provided on a circuit board due to a change in the liquid level.

  A conventional liquid level detection device is provided with a resistor made of a resistive material on a circuit board, and has a conductor path made of a conductive material such as silver or palladium and glass along the resistor, (See, for example, Patent Document 1).

  In such a liquid level detecting device, since the sliding contact slides on the hard conductor path, wear of the sliding contact has been a problem.

  Therefore, the cause of wear of the sliding contact is roughness due to minute irregularities on the surface of the conductor path, and polishing of the surface of the conductor path in order to remove the minute irregularities on the surface of the conductor path. There has been a liquid level detection device that has been polished to improve durability (for example, see Patent Document 2).

Japanese Utility Model Publication No. 62-40528 JP 11-2111540 A

  In such a liquid level detection device, the fine irregularities on the surface of the conductor path are reduced by polishing, and the wear of the sliding contact is greatly reduced and the durability is improved. However, the durability is further improved. Was desired.

  Therefore, in order to further remove minute irregularities on the surface of the conductor path, it is conceivable to polish the surface of the conductor path. However, performing the polishing operation to smooth the surface of the conductive path is a work man-hour. There was a problem that the cost increased.

  Therefore, the present invention provides a liquid level detection device that suppresses an increase in cost and improves durability.

In order to achieve the above object, the present invention provides a circuit board provided with a conductor, a sliding contact that slides on the conductor in accordance with a change in liquid level, and a slider on which the sliding contact is fixed. In the liquid level detecting device, the slider rotates about a fulcrum, and the conductor intermittently on an arc-shaped locus of the sliding contact based on the rotation of the slider. a plurality of arranged, with respect to the sliding direction of the sliding contact, is the polishing marks of the common direction as one lifting the inclination of 45 ° to 90 ° as provided in the plurality of conductors.

  Moreover, the said grinding | polishing trace consists of an unevenness | corrugation of 0.5-1.0 micrometer.

  As described above, according to the present invention, it is possible to provide a liquid level detection device that can achieve an intended purpose, suppress an increase in cost, and have improved durability.

The front view of 1st Embodiment of this invention. The principal part enlarged front view of the embodiment. Sectional drawing before grinding | polishing of the fixed electrode of the AA line in FIG. Sectional drawing after grinding | polishing of the fixed electrode of the AA line in FIG.

  1 to 4 are front views of a first embodiment of the present invention, and the present invention will be described taking a liquid level detection device provided in a fuel tank of a vehicle such as an automobile as an example.

  The liquid level detection device 1 includes a circuit board 2 such as ceramic, fixed electrodes 3a and 3b made of a conductor formed on the circuit board 2, a resistor 4 connected to the fixed electrode 3a, and a fulcrum not shown. , And a first sliding contact 6 and a second sliding contact 7 provided on the slider 5.

  9 and 10 are wiring patterns for electrically connecting the connection lands 9a and 10a and the fixed electrodes 3a and 3b. The wiring patterns 9 and 10 and the connection lands 9a and 10a are the same as the fixed electrodes 3a and 3b. It is made of a conductor. Lead wires 12 are connected to the connecting lands 9a and 10a by solder 13, respectively, and are connected to a driving means of a meter (not shown). Reference numeral 11 denotes an adjustment resistor 11.

  The fixed electrode 3a is made of a conductor and has a linear shape, and a plurality of the fixed electrodes 3a are provided. The fixed electrodes 3a are connected to the resistors 4 respectively. The conductor constituting the fixed electrode 3a is made of a metal such as silver or palladium and glass, and is baked on the circuit board 2.

  The fixed electrode 3b is made of the same conductor as the fixed electrode 3a, and its main part has a fan shape. The fixed electrode 3b includes a groove portion 14 in which the circuit board 2 is exposed inside the sector.

  The resistor 4 is provided so as to straddle the plurality of fixed electrodes 3. In the present embodiment, the resistor 4 is made of the same material as that of the adjustment resistor 11 and is formed in the same process.

  The slider 5 has a plate shape made of a metal such as white and white, and includes a first sliding contact 6 and a second sliding contact 7 made of an alloy of palladium and ruthenium.

  The first sliding contact 6 and the second sliding contact 7 are fixed to the first arm piece 51 and the second arm piece 52 having elasticity, respectively, by means such as welding. In the present embodiment, two sliding contacts 6 and 7 are provided.

  In the present embodiment, the locus of the sliding direction S between the first sliding contact 6 and the second sliding contact 7 is an arc. This is because the slider 5 rotates around a fulcrum (not shown).

  As shown in FIG. 3, each fixed electrode 3a, 3b before polishing is provided with unevenness of 5 to 7 μm. Therefore, when 2 to 3 μm is polished above the fixed electrodes 3a and 3b, polishing marks 15 are formed on the fixed electrodes 3a and 3b as shown in FIGS. The polishing mark 15 is composed of irregularities, and the crests 15a and grooves 15b of the irregularities are formed so as to extend in the vertical direction of the circuit board 2 in FIG. 1, and the center of each fixed electrode 3a, 3b. Are perpendicular to the sliding direction S of each sliding contact 6, 7, and at both ends of each fixed electrode 3 a, 3 b, to the sliding direction S of each sliding contact 6, 7, It has an inclination of about 63 °. The unevenness of the polishing mark 15 is 0.5 to 1.0 μm, which is the difference between the uneven peak 15a and the groove 15b.

  Since each sliding contact 6, 7 is larger than each fixed electrode 3 a, 3 b, the sliding contact 6, 7 does not contact the recessed portion 16 formed before polishing, and each sliding contact 6, 7 has a polishing mark 15. It will touch only the part.

  This embodiment is compared with a comparative example. In the comparative example, the polishing marks 15 are formed so as to extend in the lateral direction of the circuit board 2 in FIG. 1, that is, with an inclination of 0 ° to 27 ° with respect to the sliding direction S of the sliding contacts 6, 7. It has something.

  In both the present embodiment and the comparative example, the number of samples is 5, and the table shows the average value. In addition, the thickness of each sliding contact 6 and 7 is about 1.0 mm. When the amount of wear of the sliding contact 6 is compared, when the number of sliding times is 1 million, the comparative example is 0.121 mm for the wear of 0.421 mm, and the amount of wear is approximately It has decreased to a quarter. Moreover, when the frequency | count of sliding is 2 million times, this embodiment is 0.189 mm, and is less than the abrasion amount of 1 million times of sliding times of a comparative example.

  As described above, since the sliding direction S of each sliding contact 6, 7 has an inclination of 45 ° to 90 ° with respect to the polishing mark 15, each sliding contact 6, 7 has the polishing mark 15. As a result, point contact is made with respect to the unevenness, and wear of the sliding contacts 6 and 7 is reduced to improve durability.

  Further, by setting the unevenness of the polishing mark 15 to 0.5 to 1.0 μm, it is possible to suppress an increase in cost by suppressing the polishing work for reducing the unevenness of the polishing mark 15.

  In addition, the inclination with respect to the sliding direction S of the sliding contact 6 and 7 of the grinding | polishing trace 15 is not limited to this embodiment, 45 degrees-with respect to the sliding direction S of the sliding contact 6 and 7 A 90 ° inclination may be used.

  Further, the polishing mark 15 is at the rotation center (not shown) of the slider 5 so that the polishing mark 15 of all the fixed electrodes 3a and 3b is perpendicular to the sliding direction S of the sliding contacts 6 and 7. The fixed electrodes 3a and 3b may be polished so as to go.

  The present invention is applicable to a liquid level detection device in which a sliding contact slides on a fixed electrode on a circuit board.

DESCRIPTION OF SYMBOLS 1 Liquid level detection apparatus 2 Circuit board 3a, 3b Fixed electrode 5 Slider 6 1st sliding contact 7 2nd sliding contact 15 Polishing trace 15a Mountain 15b Groove S Sliding direction

Claims (2)

In a liquid level detection apparatus comprising: a circuit board provided with a conductor; a sliding contact that slides the conductor according to a change in the liquid level; and a slider to which the sliding contact is fixed. The mover rotates around a fulcrum, and a plurality of the conductors are intermittently arranged on an arcuate locus of the sliding contact based on the rotation of the slider. to the direction, the liquid level detecting apparatus according to claim polishing scars common direction as one lifting the inclination of 45 ° to 90 ° to the provision of the plurality of conductors. The liquid level detection device according to claim 1, wherein the polishing mark is made of irregularities of 0.5 to 1.0 μm.

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