JP2005331324A - Oil check sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil check sensor capable of accurately checking the contamination degree of oil caused by a metal powder. <P>SOLUTION: The electrode opposed to a cup-shaped electrode 9 in the sensor head 4 on the outer peripheral side of a permanent magnet is formed of a plurality of rod-shaped conductors 10 and the intervals between the conductors 10 and the electrode 9 are set so as to be stepwise become different while the resistance value Rn of the resistor 14a interposed between the conductor 10 set to a narrow interval and the electrode 9 is largely set and the conductor 10 narrow in the interval with the electrode 9 is short-circuited preceedingly. By this constitution, a change in the partial pressure voltage (n) detected by a voltmeter 15 as the output of the sensor accompanying an increase in a short-circuit number is leveled to make the short-circuit number (n) plainly and the contamination degree of oil caused by the metal powder is detected more clearly. <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 magnet, and a pair of electrodes facing each other with an axial interval is provided on the outer peripheral side of the magnet, and the amount of metal powder in the oil bath is changed by a change in resistance between the electrodes in the oil bath. (For example, refer to 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. That is, assuming that the specific resistance value of the resistor is R ₀ and the adhesion area ratio of the conductor to the end face of the resistor is S%, the resistance between the electrodes at this time is R ₀ × (100 / S) Ω. Accordingly, when the degree of oil contamination due to iron powder or the like increases, the resistance between the detected electrodes decreases. As the resistor forming the electrode, a conductive resin or conductive ceramic added with conductive carbon can be used. Instead of forming the electrode with the resistor, the resistor is disposed between the magnet and the pair of electrodes. A resistor may be applied to the outer periphery of the cylindrical insulating cover.

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

In the oil check sensor described in Patent Document 1, it is necessary to use a resistor on the outer peripheral portion of the electrode or the insulating cover disposed on the inner peripheral side thereof, so that an internal stress is applied to the resistor due to a load load or a temperature change. When this occurs, the arrangement of carbon added to the resistor changes, and the specific resistance value R _{0 of the} resistor changes. For this reason, the resistance between electrodes cannot be detected stably, and there is a problem that the degree of contamination of oil due to metal powder such as iron powder cannot be accurately checked.

  Accordingly, an object of the present invention is to provide an oil check sensor that can accurately check the degree of oil contamination by metal powder.

  In order to solve the above-described 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 an electrode facing the outer periphery of the magnet with an interval in the axial direction. In the oil check sensor for detecting the amount of metal powder in the oil bath, at least one of the opposing electrodes is formed of a plurality of conductors, and these conductors are interposed with resistors having different resistance values, respectively. A configuration is adopted in which the amount of metal powder in the oil bath is detected by a sensor output that is connected to a power source and varies depending on the number of short circuits of these conductors with the opposing electrodes.

  That is, at least one of the opposing electrodes is formed of a plurality of conductors, and these conductors are connected to a power source via resistors having different resistance values, and iron powder or the like is interposed between the opposing electrodes. By detecting the amount of metal powder in the oil bath with the sensor output that changes depending on the number of conductors that are short-circuited due to the adhesion of the metal powder conductor, the degree of contamination of the oil by the metal powder can be checked accurately. did. The reason why the resistance values of the resistors interposed between the respective conductors and the power supply are set to different values is to make it possible to arbitrarily adjust the relationship between the number of short circuits and the sensor output.

  The intervals between the plurality of conductors and the opposing electrodes are set stepwise differently, and the resistance value of the resistor interposed between the electrodes is set to be larger as the interval is set to be narrower. Therefore, the closer the conductor to the opposing electrode, the shorter the short circuit first, so the change in sensor output with increasing number of short circuits is leveled to make the number of short circuits easier to understand, and the degree of oil contamination with metal powder is further improved. It can be clearly detected.

  By setting each resistance value of the resistor so that the relationship between the number of short circuits of the conductor and the sensor output is linear, the number of short circuits can be made easier to understand.

  In the oil check sensor of the present invention, at least one of the opposing electrodes is formed of a plurality of conductors, and these conductors are connected to a power source via resistors having different resistance values, respectively. The amount of metal powder in the oil bath is detected by the sensor output that changes depending on the number of conductors that are short-circuited due to the adhesion of a metal powder conductor such as iron powder. The degree can be checked accurately.

  By setting each interval between the plurality of conductors and the facing electrode to different intervals step by step, and setting the resistance value of the resistor interposed between the electrodes to be larger as the conductor is set to have a smaller interval. Since the conductor with a narrower distance from the opposing electrode is short-circuited first, the change in sensor output accompanying the increase in the number of short-circuits is leveled to make it easier to understand the number of short-circuits, and the degree of oil contamination due to metal powder becomes clearer Can be detected.

  By setting the resistance values of the resistors so that the relationship between the number of short-circuited conductors and the sensor output is linear, the number of short-circuits can be made easier to understand.

  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 3 a through which oil flows to the sensor head portion 4.

  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.

  As shown in FIGS. 2 and 3, eight conductors 10 are provided around the rod-like member 5 at equal intervals in the circumferential direction, and the tip surface of each conductor 10 forming the sensor head portion 4 and a cup-like shape are provided. The distance from the end face of the electrode 9 is set stepwise at different intervals. The cup-shaped electrode 9 is secured to the distal end side of the rod-shaped member 5 by a retaining ring 11.

  As shown in FIGS. 1 and 3, the base end of the rod-shaped member 5 is connected to the negative side of the DC power supply 13 by a conducting wire 12 a, and the base end of each conductor 10 has the smallest distance from the end face of the electrode 9. A resistor 14a having a large resistance value Rn (n = 1 to 8) is interposed in order from one to the other, and is connected together by a conductor 12b. Further, a resistor 14b having a resistance value Rb is interposed, and the conductor 12c is connected to the DC power supply 13 plus. Connected to the side. Further, a voltmeter 15 for detecting a divided voltage V of the sensor head unit 4 to be described later is provided between the lead wire 12b connecting the base end of each conductor 10 via each resistor 14a and the negative side of the DC power supply 13. Is provided.

  In this embodiment, when the supply voltage Vo of the DC power supply 13 is 5 V, the resistance value Rb of the resistor 14 b is 0.5 kΩ, and the short-circuiting is performed in order from the conductor 10 having a small distance from the end face of the electrode 9, the number of short circuits n The resistance value Rn of each resistor 14a is set as follows so that the relationship between the divided voltage V (n) of the sensor head unit 4 detected by the voltmeter 15 is linear.

（１）式と、（１）式における短絡個数をｎ−１とした分圧電圧Ｖ（ｎ−１）の式との差をとって変形すると、ｎ番目に短絡する導電体１０の抵抗１４ａの抵抗値Ｒｎは次式で表される。
１／Ｒｎ＝Ｖｏ・[Ｖ（ｎ−１）−Ｖ（ｎ）]／[Ｖ（ｎ−１）・Ｖ（ｎ）・Ｒｂ] （２） The relationship between the number n of short-circuited conductors 10 and the divided voltage V (n) detected by the voltmeter 15 is expressed by the following equation.

When the difference is taken between the equation (1) and the equation of the divided voltage V (n−1) where the number of short circuits in the equation (1) is n−1, the resistance 14a of the conductor 10 that is n-th short-circuited. The resistance value Rn is expressed by the following equation.
1 / Rn = Vo. [V (n-1) -V (n)] / [V (n-1) .V (n) .Rb] (2)

  Here, while substituting the numerical values of Vo = 5V and Rb = 0.5 kΩ into the expression (2), the divided voltage V (8) when all the eight conductors 10 are short-circuited is set to 0.5V, and the short-circuit is performed. The amount of change in the divided voltage V (n-1) -V (n) = [Vo-V (8)] / 8 = 0.5625 V when the number n is increased by 1, and each resistance value Rn is set to R1 = 3.94 kΩ, R2 = 3.06 kΩ, R3 = 2.28 kΩ, R4 = 1.62 kΩ, R5 = 1.07 kΩ, R6 = 0.63 kΩ, R7 = 0.31 kΩ, R8 = 0.09 kΩ Set.

FIG. 4 shows the relationship between the number n of short-circuited conductors 10 and the divided voltage V (n) detected by the voltmeter 15 when the resistance value Rn of each resistor 14a is set as described above. When the oil is clean and the amount of metal powder adhering to the sensor head portion 4 is small and all the conductors 10 are not short-circuited with the electrodes 9, the resistance between the electrodes in the sensor head portion 4 is infinite, and the voltmeter The divided voltage V (0) detected at 15 is 5V which is equal to the supply voltage V ₀ .

  Next, when the oil contamination progresses, the conductor 10 is short-circuited in order from the one having the narrower gap with the electrode 9, and the divided voltage V (n) decreases by about 0.56V each time the number n of short-circuits increases by one. When all the conductors 10 are short-circuited, the voltage becomes 0.5V. Therefore, the divided voltage (n) detected by the voltmeter 15 changes linearly as the number of short circuits n of the conductor 10 increases, so that the degree of oil contamination due to metal powder can be clearly detected. .

  In the embodiment described above, the number of rod-shaped conductors is eight. However, the number of conductors can be arbitrarily set, and the resistance interposed between the electrodes can be set according to the number of these conductors. The resistance value can also be set so that the relationship between the number of short circuits n and the divided voltage V (n) is linear. Note that the plurality of conductors are not necessarily rod-shaped.

  In the above-described embodiment, a permanent magnet is used as a magnet for attracting metal powder to the sensor head portion, and only one electrode facing the sensor head portion is formed of a plurality of conductors. It can also be formed of a plurality of conductors, and an electromagnet can be used as the magnet.

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. The graph which shows the relationship between the short circuit number n of a conductor, and the divided voltage V (n).

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 Insulation cover 9 Electrode 10 Conductor 11 Retaining ring 12a, 12b, 12c Conductor 13 DC power supply 14a, 14b Resistance 15 Voltmeter

Claims (3)

  An oil for detecting the amount of metal powder in the oil bath by providing a magnet on the outer periphery of the tip of the rod-shaped member inserted into the oil bath and providing electrodes facing the outer periphery of the magnet with an interval in the axial direction. In the check sensor, at least one of the opposing electrodes is formed of a plurality of conductors, and these conductors are connected to a power source via resistors having different resistance values, respectively, and the opposing of these conductors An oil check sensor characterized in that the amount of metal powder in the oil bath is detected by a sensor output that varies depending on the number of short circuits with the electrode.   The intervals between the plurality of conductors and the opposing electrodes are set to different intervals step by step, and the resistance value of the resistor interposed between the electrodes is set to be larger as the conductor is set to be narrower. The oil check sensor according to claim 1.   The oil check sensor according to claim 2, wherein each resistance value of the resistor is set so that a relationship between the number of short circuits of the conductor and the sensor output is linear.

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