JP4716965B2 - Debris detection sensor - Google Patents

Description

  The present invention relates to a fragment detection sensor for detecting non-conductive fragments mixed in a liquid such as lubricating oil.

Conventionally, a metal check sensor or an oil check has been used as a device for detecting metal fragments or metal powders generated by wear or damage of engines, transmissions, bearings, etc. in lubricating oil for automobiles, aircraft, helicopters, etc. Metal piece detection devices called sensors or debris sensors have been proposed (Patent Documents 1 to 5).
Such a metal piece detection device is used as a means for inspecting the soundness of various devices such as an engine, a gear box, a bearing, etc. Can be obtained before it occurs.
Japanese Unexamined Patent Publication No. 55-052943 JP-A-61-253455 JP 2000-32248 A Japanese Patent No. 2703502 Japanese Patent No. 2865857

At present, there is a demand for miniaturization and high speed particularly in aircraft jet engines. Conventionally, in bearings for main shafts of aircraft jet engines, metal materials have been used for the rolling elements. However, it is difficult to achieve higher speeds with the current rolling element materials. In order to withstand high speed, the rolling elements of the bearing need to be ceramic balls or rollers made of silicon nitride (Si3N4) or the like. In addition, when ceramic balls or ceramic rollers are applied to the jet engine bearing, the performance is greatly improved, and consequently the efficiency of the jet engine is improved, which may reduce the environmental load.
On the other hand, conventional metal piece detection devices can detect only metal, magnetic or conductive material fragments, and cannot detect ceramic materials characterized by non-metal, non-magnetic and non-conductivity. It was. Therefore, for example, in the case of a bearing using a ceramic rolling element, it is impossible to obtain information on deterioration or damage of the rolling element using the metal piece detection device before a destructive failure occurs. Therefore, at present, the bearing having such a configuration is used only for aircraft having limited applications.

  An object of the present invention is to provide a debris detection sensor that can detect debris of a material characterized by non-metal, non-magnetic, and non-conductive properties such as a ceramic material mixed in a liquid.

The debris detection sensor according to the present invention is a sensor for detecting debris mixed in a liquid, and is configured to move two facing flat plates and at least one of the two flat plates in a facing direction to move the two flat plates. And a measuring / determining means for detecting the presence / absence, size, or accumulation amount of the fragments by measuring the distance between the two plates.
According to this configuration, one of the two flat plates is operated, the capacitance between the two flat plates is measured, and the presence / absence, size, or accumulation amount of debris is determined from the measured value. Therefore, it is possible to estimate the state of fragments (the presence or absence of fragments and the size of the fragments) mixed in a liquid such as lubricating oil to be inspected.
In addition, when the above debris detection sensor is incorporated in an automobile, aircraft, helicopter, etc., it is possible to monitor the state of debris mixed in the lubricating oil. Can inform you that a replacement is necessary. In addition, the detected information can be obtained before a destructive failure occurs due to deterioration or damage.

  In the present invention, the measurement / determination means may measure the distance between the two flat plates by a capacitance. According to the capacitance, it is possible to accurately measure the distance between two flat plates with a simple configuration.

  In this invention, the measuring means may estimate the capacitance by applying an alternating current and measuring impedance. According to the impedance measurement, it can be measured with a simple configuration with high accuracy.

  In the present invention, the measurement means includes an oscillator that converts the change in capacitance into a change in frequency, and a frequency-corresponding capacitance estimation means that estimates the capacitance from the oscillation frequency of the oscillator. May be. As described above, when the oscillator and the frequency-corresponding capacity estimation means are provided, detection can be performed with high accuracy.

  In the present invention, the measuring means is a charging / discharging means that repeatedly causes charging and discharging between the two flat plates, and a charging / discharging time that estimates the capacitance from a charging / discharging time caused by an excessive phenomenon in the repeated charging and discharging. It may consist of a discharge time corresponding capacitance estimation means. Even when a charge / discharge time-corresponding capacitance estimation means is provided, detection can be performed with high accuracy.

  In the present invention, a linear motion actuator may be used as the flat plate moving mechanism. When a linear actuator is used, unlike the case where a rotational drive source is used, a mechanism for converting rotation into linear motion is not required, and the fragment detection sensor can be configured simply and compactly.

  In the case of the present invention, the linear actuator may be an electromagnetic type, a hydraulic type or a pneumatic type.

  The debris detection sensor according to the present invention is a sensor for detecting debris mixed in a liquid, and is configured to move two facing flat plates and at least one of the two flat plates in a facing direction to move the two flat plates. Since it has a plate moving mechanism that sandwiches a piece into the plate and a measurement / judgment means for detecting the presence, size, or accumulated amount of the piece by measuring the distance between the two plates, It is possible to detect non-metallic, non-magnetic, non-conducting material fragments such as mixed ceramic materials and obtain the information before the destructive failure occurs from deterioration or damage by the detected information be able to.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration diagram of a fragment detection sensor of this embodiment. This debris detection sensor is a sensor for detecting debris of a material characterized by non-metal, non-magnetic, and non-conductivity mixed in a liquid to be inspected, and two flat plates 5, 7 facing each other; A flat plate moving mechanism 9 that moves at least one of the two flat plates 5 and 7 in a facing direction to sandwich a broken piece 13 (FIG. 3) between the two flat plates 5 and 7, and the two flat plates 5 and 7. And measuring / determining means 16 for detecting the presence / absence, size, or accumulation amount of the debris 13 by measuring the distance between them. In the case of this debris detection sensor, the lubricating oil is the liquid to be inspected.

  The two flat plates 5 and 7 and the flat plate moving mechanism 9 are incorporated in the sensor unit 1. This sensor unit 1 has a base member 4 provided with an oil passage 4a through which lubricating oil to be inspected flows, and an oil supply pipe 2 is connected to one end of the oil passage 4a. An oil drain pipe 3 is connected to the end. In this case, the lubricating oil flows from the oil path 2 a of the oil supply pipe 2 through the oil path 4 a of the base member 4 to the oil path 3 a of the oil discharge pipe 3. For example, the oil supply pipe 2 is connected to a pipe for collecting lubricating oil used in an engine, a gear box, a bearing, and the like, and the oil drain pipe 3 is connected to a pipe to an oil tank.

  One flat plate 5 of the two flat plates 5 and 7 is a fixed flat plate made of a conductive material. The base member 4 is interposed in the middle of the oil passage 4a of the base member 4 via a flat plate fixing member 6 made of an insulating material. It is fixed in an electrically insulated state. The fixed flat plate 5 is arranged so that the surface thereof faces the oil passage 4a.

  The flat plate moving mechanism 9 is a linear motion actuator composed of a push-pull solenoid or the like, and an actuator fixing member 10 so that the movable shaft 9a can advance and retract in a direction perpendicular to the penetrating direction of the oil passage 4a of the base member 4. It is being fixed to the base member 4 via. A state in which the other flat plate 7 of the two flat plates 5 and 7 is electrically insulated from the tip of the movable shaft 9a of the linear actuator 9 via a flat plate fixing member 8 made of an insulating material. It is fixed with. The flat plate 7 is a movable flat plate that can be moved forward and backward integrally with the movable shaft 9a of the linear actuator 9. The flat plate 7 is made of a conductive material in the same manner as the fixed flat plate 5, and penetrates the base member 4 to enter the oil passage 4a. To face the fixed flat plate 5. Here, an example in which a push-pull solenoid is used as the linear actuator 9 is shown, but any type of linear actuator can be used. For example, a combination of an electric motor and a ball screw may be used, or an air pressure or hydraulic pressure may be used. When the linear actuator 9 is operated, the movable flat plate 7 installed on the movable shaft 9 a via the flat plate fixing member 8 advances and retreats, and approaches or moves away from the fixed flat plate 5.

The movable shaft 9a of the linear actuator 9 is urged in the advancing direction by a compression spring 12 interposed between a spring receiving member 11 fixed to the rear end portion and the actuator fixing member 10.
FIG. 1 shows a state in which power is supplied to the linear actuator 9. At this time, the movable shaft 9 a is retracted by compressing the compression spring 12, and the movable flat plate 7 is located away from the fixed flat plate 5. On the other hand, in a state where the power is not applied to the linear actuator 9, as shown in FIG. 2, the force is restored by the compression spring 12 that is compressed when the power is turned on, and the movable plate 7 moves to a position where it contacts the fixed plate 5. To do. Since the movable plate 7 and the fixed plate 5 are in contact with each other, the movable plate 7 is preloaded by the compression spring 12, so that the movable plate 7 and the fixed plate 5 are in contact with each other at a constant pressure.

  The measurement / determination unit 16 includes a capacitance measurement unit 14 and a determination unit 15. The capacitance measuring means 14 is a means for measuring the capacitance between the movable flat plate 7 and the fixed flat plate 5, and the electrodes 14 a and 14 b that are input terminals of the capacitance measuring means 14 are respectively connected to the movable flat plate 7 and the movable flat plate 7. Connected to the fixed plate 5. The determination means 15 is a means for determining the state of the debris 13 (FIG. 3) in the lubricating oil from the measurement value of the capacitance measurement means 14, for example, a table or an arithmetic expression that defines the relationship between the measurement value and the determination result. The determination rule is compared with the measurement value, and the determination result is output for the presence / absence, size, accumulated amount, etc. of the fragments.

Next, an operation for detecting fragments in the lubricating oil by the fragment detection sensor will be described.
As described above, when the linear actuator 9 is powered on, the movable shaft 9a moves backward as shown in FIG. 1, and the movable flat plate 7 installed on the movable shaft 9a via the flat plate fixing member 8 is fixed to the fixed flat plate 5. Get away from. At this time, the compression spring 12 installed between the spring receiving member 11 fixed to the movable shaft 9a and the actuator fixing member 10 is compressed.

Next, as the liquid to be inspected, the lubricating oil used in the engine, gearbox, bearing, etc. is passed through the oil passage 2a of the oil supply piping 2 and the oil passage 4a of the base member 4 to the oil in the oil discharge piping 3. In this state, when the application of power to the linear actuator 9 is stopped, the movable flat plate 7 approaches the fixed flat plate 5 integrally with the movable shaft 9a by the restoring force of the compression spring 12. Advance.
At this time, in the lubricating oil flowing through the oil passage 4a of the base member 4, as shown in FIG. 3, a non-metallic, non-magnetic, non-conductive material such as a ceramic material caused by wear or damage to the engine, gear box, bearing, etc. If a piece 13 of a material having a characteristic is mixed, the piece 13 is sandwiched between the movable flat plate 7 and the fixed flat plate 5. Thereby, a gap d is generated between the movable flat plate 7 and the fixed flat plate 5 by the thickness of the debris 13. Due to the gap d, a capacitance C is formed between the two flat plates 5 and 7.

By the way, in general, the capacitance C between the parallel plates is C = εo εr S / d (1)
It is known that That is, the capacitance C [F] is obtained by multiplying the dielectric constant εo in vacuum (8.854 × 10 ⁻¹² [F / m]) by the dielectric constant εr of the lubricating oil and the area S [m ² ] of the parallel plate. The value obtained by dividing the above by the gap d [m] between the parallel plates. In this embodiment, since the dielectric constant εr of the lubricating oil and the area S of the parallel plate are constant, the value of the capacitance C depends on the gap d between the parallel plates, that is, between the movable plate 7 and the fixed plate 5. .
Therefore, the capacitance C between the two flat plates 5 and 7 is measured by the capacitance measuring means 14, and the value of the gap d between the flat plates 5 and 7 is detected. Accumulated amount can be estimated.

  On the other hand, when there is no debris 13 between the two flat plates 5 and 7, a gap d is formed by a very small film of lubricating oil, or the flat plates 5 and 7 are in contact with each other. In the case of the extremely small gap d due to the lubricating oil, the electrostatic capacity C shows a considerably large value as compared with the case where the debris 13 is sandwiched. Further, when the flat plates 5 and 7 are in contact with each other, the conductive state is established. Therefore, the presence or absence of the fragments 13 can be determined from these values. The determination of the presence / absence or size of the debris 13 or the accumulated amount is determined by the determination unit 15 based on the measurement value of the capacitance measurement unit 14. For the capacitance measuring means 14, a measuring instrument such as a capacitance meter can be used.

  FIG. 4 shows a configuration example of the capacitance measuring means 14 which is a component of the measuring / determining means 16 in the fragment detection sensor of FIG. This capacitance measuring means 14 is composed of an oscillator 20 and a current measuring means 21 connected in series, and an alternating current is passed from the oscillator 20 to the movable flat plate 7 and the fixed flat plate 5 so that the capacitance C between the flat plates 5 and 7 is obtained. It is converted into impedance and measured by the current measuring means 21. In this case, the capacitance C can also be obtained from the measured impedance. Other configurations are the same as those in FIG.

FIG. 5 shows another configuration example of the capacitance measuring means 14 which is a constituent element of the measuring / determining means 16 in the fragment detection sensor of FIG. The capacitance measuring means 14 includes an oscillator 30 constituted by an OP amplifier 32 and a frequency corresponding capacity estimating means 31 for estimating the capacitance from the oscillation frequency of the oscillator 30. A flat plate is obtained from the measured frequency of the oscillator 30. The capacitance C between 5 and 7 is estimated. The oscillator 30 in this case is called a relaxation oscillator and is configured by connecting resistors 33Ra, 33Rb, 33Rt and a capacitor 33Ct to an OP amplifier 32. If the resistance values of the resistors 33Ra, 33Rb, 33Rt are Ra, Rb, Rt, and the capacitance of the capacitor 33Ct is Ct, the oscillation frequency f is approximately
f = 1 / (2Rt Ct) (2)
It is known that Here, the capacitance C is estimated by replacing the capacitor 33Ct of the oscillator 30 with the capacitance C between the flat plates 5 and 7.

  FIG. 6 shows still another configuration example of the capacitance measuring unit 14 which is a component of the measuring / determining unit 16 in the fragment detection sensor of FIG. The capacitance measuring unit 14 includes a charging / discharging unit 40 and a charge / discharge time-corresponding capacitance estimating unit 41 that estimates a capacitance from a charging / discharging time caused by an excessive phenomenon in charging and discharging. The charging / discharging means 40 connects the series circuit portion of the charging resistor 42 and the charging switch 43 in series with the measured capacitance Ct, and parallels the series circuit portion of the discharging switch 44 and the discharging resistor 45 with the measured capacitance Ct. It is a connected circuit. The charge / discharge time-corresponding capacitance estimation unit 41 measures a voltage measurement unit 46 that monitors a charge / discharge voltage in the charge / discharge unit 40 and a time until the voltage monitored by the voltage measurement unit 46 reaches a specified voltage. Thus, the judgment means 47 for estimating the capacitance Ct to be measured is formed.

  In this case, for example, the charging switch 43 is turned on to start charging, the charging voltage of the capacitance Ct to be measured is monitored by the voltage measuring means 46, and the charging time until the charging voltage reaches the specified voltage is determined. By measuring by means 47, the measured capacitance Ct can be estimated. Alternatively, with respect to the measured capacitance Ct that has been charged to a predetermined voltage in advance, the discharge switch 44 is turned on to start discharging, and the discharge voltage of the measured capacitance Ct is monitored by the voltage measuring means 46. By measuring the discharge time until the discharge voltage reaches the specified voltage by the judging means 47, the measured capacitance Ct can be estimated. Here, the capacitance Ct is estimated by replacing the capacitance Ct to be measured with the capacitance C between the flat plates 5 and 7.

As described above, in the fragment detection sensor of this embodiment, the movable plate 7 is operated, and the capacitance C between the movable plate 7 and the fixed plate 5 is measured by the capacitance measuring means 14, and this capacitance measurement is performed. Since the determination means 15 determines the presence / absence, size, or accumulation amount of the fragments 13 from the measured value of the means 14, the state of the fragments 13 mixed in the lubricating oil can be estimated.
In addition, when the above debris detection sensor is incorporated in an automobile, aircraft, helicopter, etc., it is possible to monitor the state of debris mixed in the lubricating oil. It is possible to inform that replacement is necessary, and safety is improved. In addition, since the life and aging of machine parts can be predicted, there is no need for unnecessary or delayed replacement of parts, thereby improving economy.

  FIG. 7 shows another embodiment of the fragment detection sensor of the present invention. In this embodiment, in the embodiment shown in FIG. 1, a recording means 50 is added to the next stage of the judging means 15 so that the state of the debris 13 mixed in the lubricating oil can be monitored in real time. Any one of the capacitance measuring means 14 shown in FIGS. 4 to 6 may be used. Note that the determination unit 15 may determine that a problem has occurred because the value of the variation in capacitance measured by the capacitance measurement unit 14 exceeds a predetermined threshold.

It is a schematic block diagram at the time of power activation of the fragment detection sensor concerning 1st Embodiment of this invention. It is a schematic block diagram at the time of the power supply stop of the same fragment detection sensor. It is explanatory drawing of the detection operation of the same fragment detection sensor. It is explanatory drawing of the detection operation at the time of using one structural example as an electrostatic capacitance measurement means in the fragment detection sensor. It is a circuit diagram which shows the other structural example of the electrostatic capacitance measurement means in the same fragment detection sensor. It is a circuit diagram which shows the further another structural example of the electrostatic capacitance measurement means in the fragment detection sensor. It is a schematic block diagram at the time of power activation of the fragment detection sensor concerning other embodiment of this invention.

Explanation of symbols

5 ... Fixed flat plate 7 ... Movable flat plate 9 ... Linear motion actuator (flat plate moving mechanism)
13 ... Fragment 14 ... Capacitance measurement means 15 ... Determination means 16 ... Measurement / determination means 30 ... Oscillator 31 ... Frequency corresponding capacity estimation means 40 ... Charge / discharge means 41 ... Charge / discharge time correspondence capacitance estimation means

Claims (7)

  A sensor for detecting debris mixed in a liquid, comprising two opposing flat plates, and a flat plate moving mechanism for moving the at least one of the two flat plates in a facing direction to sandwich the debris between the two flat plates And a debris detection sensor having measurement / determination means for detecting the presence / absence, size, or accumulation amount of the debris by measuring a distance between the two flat plates.   2. The debris detection sensor according to claim 1, wherein the measurement / determination means measures a distance between the two flat plates by a capacitance.   3. The debris detection sensor according to claim 2, wherein the measuring unit estimates the capacitance by applying an alternating current and measuring an impedance.   3. The debris detection according to claim 2, wherein the measurement means includes an oscillator that converts the change in capacitance into a change in frequency, and a frequency-corresponding capacitance estimation means that estimates the capacitance from the oscillation frequency of the oscillator. Sensor.   In Claim 2, the said measurement means estimates the said electrostatic capacitance from the charging / discharging means which repeatedly produces charge and discharge between the said 2 flat plates, and the charging / discharging time which arises by the transient phenomenon in the repetition of the charge and discharge. A debris detection sensor comprising a charge / discharge time-capable capacitance estimation means.   6. A debris detection sensor according to claim 1, wherein a linear motion actuator is used as the flat plate moving mechanism. 7. The debris detection sensor according to claim 6, wherein the linear motion actuator is of an electromagnetic type, a hydraulic type or a pneumatic type.

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