JP2005337945A - Oil check sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the sensing sensitivity of an oil check sensor by preventing the adsorption of a metal powder to a part other than a sensing part. <P>SOLUTION: The adsorption of the metal powder to the part other than the sensor head part 4 being the sensing part is prevented by covering the exposed surface in an oil bath excepting the end surface of the cup-shaped electrode 9, which is opposed to a plurality of rod-shaped conductors 10 on the outer peripheral side of a permanent magnet 7, with a shielding member 12 for preventing the adsorption of the metal powder to enhance the sensing sensitivity of the oil check sensor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an oil check sensor that checks the degree of contamination of automobile mission oil, engine oil, and the like.

  A rod-like member inserted in an oil bath is installed in an oil container for automobile mission oil, engine oil, etc., and checks the degree of oil contamination caused by metal powder such as iron powder caused by wear of parts. A magnet is provided on the outer periphery of the tip of the metal, and a pair of electrodes are provided on the outer periphery of the magnet so as to face each other at an interval in the axial direction. There is one that detects the amount (see, for example, Patent Document 1). In what is described in Patent Document 1, at least one of the pair of electrodes is formed of a resistor, and varies depending on the adhesion area of a conductor such as iron powder that is magnetically attracted to the outer peripheral side of the magnet and adheres to the end surface of the resistor. The resistance between the electrodes is detected.

  In addition, the present inventor uses at least one of the opposing electrodes as an oil check sensor that can stably check the degree of oil contamination without using a resistor whose specific resistance value fluctuates due to a load load, a temperature change, or the like. The number of metal powders in the oil bath is detected based on the number of short-circuits with the opposing electrodes of these conductors (Japanese Patent Application No. 2004-91029). As a means for measuring the number of short-circuited conductors, a method is adopted in which a plurality of conductors are individually connected to a power source via a fixed resistance or energized reactant.

JP 2002-286697 A (page 2-4, Fig. 1-4)

  In the oil check sensor that detects the amount of metal powder in the oil bath based on the number of short-circuited conductors described above, the electrodes facing each other on the outer peripheral side of the magnet are easily magnetized, including the electrodes formed of a plurality of conductors. The metal powder in the oil bath is adsorbed on the exposed surfaces of these electrodes. For this reason, there is a problem that the amount of metal powder adsorbed on the outer peripheral side of the magnet between the opposing electrodes as the sensing unit is reduced, and the sensing sensitivity is lowered.

  Then, the subject of this invention is preventing the adsorption | suction of the metal powder to parts other than a sensing part, and improving the sensing sensitivity of an oil check sensor.

  In order to solve the above problems, the present invention provides a magnet on the outer periphery of the tip of a rod-shaped member inserted into an oil bath, and provides electrodes facing each other with an axial interval on the outer periphery of the magnet. An oil check sensor for detecting the amount of metal powder in the oil bath by forming at least one of these opposing electrodes with a plurality of conductors and measuring the number of short circuits with the opposing electrodes of these conductors In the above, a configuration is adopted in which at least a part of the exposed surface in the oil bath excluding the facing surfaces of the electrodes facing each other is covered with a shielding member for preventing the adsorption of the metal powder.

  That is, at least a part of the exposed surface in the oil bath excluding the facing surfaces of the electrodes facing each other is covered with a shielding member that prevents the adsorption of the metal powder, thereby adsorbing the metal powder to a portion other than the sensing portion. Preventing it and increasing the sensing sensitivity of the oil check sensor.

  The shielding member may be formed of a nonmagnetic material such as plastic, aluminum, or copper, for example.

  In the oil check sensor according to the present invention, at least a part of the exposed surface in the oil bath excluding the facing surfaces of the electrodes facing each other is covered with a shielding member that prevents the adsorption of metal powder. It is possible to increase the sensing sensitivity of the oil check sensor by preventing the metal powder from adsorbing to the portion.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. This oil check sensor is used to check the degree of dirt caused by metal powder of the mission oil of an automobile. As shown in FIG. 1, the oil check sensor is screwed to the lower portion of the side wall of the mission oil oil pan A with a nut 2 attached to the casing 1. The head cover 3 screwed to the inner periphery of the nut 2 is inserted into the oil bath in the oil pan A, and the sensor head portion 4 is provided in the head cover 3. The head cover 3 is provided with a plurality of holes 3a through which oil flows to the sensor head part 4 as a sensing part.

  At the center of the casing 1, a rod-like member 5 formed of a conductor is held by a holding member 6 fitted in the casing 1, and a ring-like shape is formed on the outer periphery of the tip of the rod-like member 5 inserted into the head cover 3. On the outer peripheral side of the cylindrical insulating cover 8 on which the permanent magnet 7 is mounted and covering the outer periphery thereof, the end surface of the cup-shaped electrode 9 attached to the bar-shaped member 5 and the holding member around the bar-shaped member 5 The sensor head portion 4 is formed so that the tip surfaces of the plurality of rod-like conductors 10 forming the other electrode held by the 6 are opposed to each other with an interval in the axial direction.

  The cup-shaped electrode 9 is secured to the distal end side of the rod-shaped member 5 by a retaining ring 11, and the exposed surface excluding the end surfaces facing the plurality of rod-shaped conductors 10 is covered with a shielding member 12 formed of a nonmagnetic material. It has been broken. Therefore, the adsorption of the metal powder to a wide exposed surface other than the end face of the cup-shaped electrode 9 magnetized by the permanent magnet 7 is prevented.

  As shown in FIG. 2, six rod-shaped conductors 10 are provided around the rod-shaped member 5 at equal intervals in the circumferential direction. In addition, since the exposed surface in the oil bath of these rod-shaped conductors 10 is not so wide, in this embodiment, these exposed surfaces are not covered with the shielding member.

  As shown in FIG. 1 and FIG. 3, the distance between the end surface of each conductor 10 forming the sensor head portion 4 and the end surface of the cup-shaped electrode 9 is set stepwise at different intervals. The base end of the rod-shaped member 5 that is electrically connected to the cup-shaped electrode 9 is connected to the minus side of the DC power supply 13 by a conducting wire 14a. The base end of each conductor 10 is connected to the substrate 16 with a fixed resistor 15a interposed therebetween. Further, the substrate 16 is connected to the positive side of the DC power supply 13 with a conductive wire 14b with a fixed resistor 15b interposed therebetween. Yes. A voltmeter 17 for detecting the divided voltage V of the sensor head unit 4 is provided between the substrate 16 and the negative side of the DC power supply 13.

In the oil check sensor described above, when the oil contamination progresses, the plurality of conductors 10 are sequentially short-circuited starting from the one having a narrow gap with the electrode 9. Assuming that the supply voltage of the DC power supply 13 is V ₀ , the resistance value of each fixed resistor 15a is R _{1 to} R _{6 in} order from the _{one having the} smallest distance to the electrode 9, and the resistance value of the fixed resistor 15b is R _b , n pieces The resistance R between the electrodes when the conductor 10 is short-circuited is expressed by equation (1), and the divided voltage V of the sensor head portion 4 changes in a stepwise manner according to equation (2).
1 / R = 1 / R ₁ + 1 / R ₂ +... + 1 / R _n (1)
V = V ₀ · R / (R + R _b ) (2)
When the oil is clean and the amount of metal powder adhering to the sensor head 4 is small and the number of shorts of the conductor 10 is zero, the resistance R between the electrodes becomes infinite, and the divided voltage V of the sensor head 4 Is equal to the supply voltage V ₀ .

  Therefore, by comparing the divided voltage V detected by the voltmeter 17 with the value calculated by the equation (2), the number of short-circuits of the conductor 10 can be measured, and the degree of contamination of oil due to metal powder is checked. be able to.

  In the above-described embodiment, only the cup-shaped electrode is covered with the shielding member, but the other electrode formed of a plurality of rod-shaped conductors may be covered with the shielding member. Although the number of rod-shaped conductors is six, the number of conductors can be set arbitrarily, and the shape does not necessarily have to be rod-shaped. Further, as a means for detecting the number of short-circuited conductors, a fixed resistor is interposed between the conductors, but it is also possible to interpose a miniature lamp that is turned on when each conductor is short-circuited.

Cutaway longitudinal sectional view showing an embodiment of an oil check sensor Sectional view along the line II-II in FIG. FIG. 1 is a conceptual diagram showing the sensor head portion of FIG. 1 and its peripheral circuits.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 Nut 3 Head cover 3a Hole 4 Sensor head part 5 Bar-shaped member 6 Holding member 7 Permanent magnet 8 Insulating cover 9 Electrode 10 Conductor 11 Retaining ring 12 Shielding member 13 DC power supply 14a, 14b Conductive wires 15a, 15b Fixed resistance 16 Substrate 17 voltmeter

Claims (2)

  A magnet is provided on the outer periphery of the tip of the rod-shaped member inserted into the oil bath, and electrodes facing each other with an axial interval are provided on the outer periphery of the magnet, and at least one of these facing electrodes is attached to a plurality of In an oil check sensor that is formed of a conductor and measures the number of short-circuits with the opposing electrodes of these conductors to detect the amount of metal powder in the oil bath, the above-described electrodes except for the opposing surfaces of the electrodes facing each other An oil check sensor characterized in that at least a part of an exposed surface in an oil bath is covered with a shielding member for preventing adsorption of the metal powder.   The oil check sensor according to claim 1, wherein the shielding member is made of a nonmagnetic material.

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