JP2008107151A - Broken piece detecting sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a broken pieces detecting sensor capable of stably detecting the existence, size or accumulation quantity of broken pieces mixed in a fluid independently of the quantity of the mixed broken pieces. <P>SOLUTION: This broken pieces detecting sensor, which detects broken pieces mixed in a fluid, comprises: three electrodes (5A, 5B, 7): an electrode shifting mechanism 9 for sandwiching the broken pieces between two electrodes with shifting at least one electrode 7 of the three electrodes: a measuring/determining means 17. The measuring/determining means 7 detects one of existence, size and quantity of accumulation by measuring the gap between the two sandwiching electrodes. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a debris detection sensor that detects debris mixed in a fluid such as lubricating oil.

Conventionally, a metal check sensor or an oil check is used as a device for detecting that metal debris or powder generated by wear or damage of engines, transmissions, bearings, etc. is mixed 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 metal piece detection devices are used as means for inspecting the soundness of various devices such as engines, gearboxes, bearings, etc., and information on deterioration in each part of the device to be inspected is a destructive failure in these parts. 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 not possible to obtain information on deterioration or damage 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.

  Therefore, as a debris detection sensor that solves such a problem, two facing flat plates are provided, and at least one of these two flat plates is moved in the facing direction by a flat plate moving mechanism to detect debris mixed in the fluid. A gap sensor is provided so as to be sandwiched between the two flat plates, and a gap change between the two flat plates in this state is detected as a change in capacitance, a change in inductance, or the like. A configuration that detects the size, the size, or the accumulated amount is conceivable.

  However, in this configuration, when a fluid such as lubricating oil to be inspected is flowed between the two flat plates and the fragments in the fluid are sandwiched between the two flat plates, there are only a few fragments to be detected in the fluid. Since the probability that the debris is caught becomes low, it is necessary to enlarge the detection region as much as possible to increase the detection probability.

  An object of the present invention is to provide a debris detection sensor that can stably detect the presence, size, or accumulation amount of debris mixed in a fluid irrespective of the amount of debris mixed.

The fragment detection sensor according to the present invention is a fragment detection sensor that detects a fragment mixed in a fluid, and includes three electrodes. By moving at least one of the three electrodes, any one of the two electrodes is moved. An electrode moving mechanism for sandwiching the debris on the surface, and a measurement / determination means for detecting any of the presence / absence, size, and accumulation amount of the debris by measuring a gap between two sandwiched electrodes. is there.
According to this configuration, by moving at least one of the three electrodes by the electrode moving mechanism, the debris is sandwiched between any two electrodes, and the gap between the two sandwiched electrodes is measured by the measurement / judgment means. Therefore, it is assumed that the presence / absence, size, and accumulation amount of debris is detected, so that the probability of debris being sandwiched between the two electrodes increases, and the presence / absence / size / accumulation of debris mixed in the fluid The amount can be detected stably without being influenced by the amount of debris to be mixed.
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.

  In the present invention, among the three electrodes, gap measuring means for measuring a gap is provided between the upper two electrodes and between the lower two electrodes, respectively, and the electrode moving mechanism is provided between the upper two electrodes and The center electrode may be moved up and down so that the debris is sandwiched between the two lower electrodes. In this configuration, the detection operation can be performed at both ends of one stroke of the center electrode, and the efficiency of the detection operation can be improved.

  In this invention, an electrode moving mechanism for operating the central electrode is installed outside the flow path for flowing the fluid, and this electrode moving mechanism is provided on one of the two electrodes on the fixed side. You may move a movable electrode through the penetration body which penetrated the hole. In the case of this configuration, the three electrodes can be arranged in a compact manner.

  In the present invention, the measurement / judgment means includes a capacitance measurement means for measuring a capacitance between two electrodes sandwiching a debris, and a gap between the two electrodes from an output of the capacitance measurement means. It may be configured by a determination unit that estimates the size.

  In the present invention, the measurement / judgment means has a displacement sensor for measuring a gap between two electrodes sandwiching the debris. From the output of the capacitance measurement means and the output of the displacement sensor, the 2 It is good also as what has the electroconductive / nonelectroconductive discrimination | determination part which discriminate | determines the electroconductivity and nonelectroconductive of the fragment pinched | interposed between two electrodes. In the case of this configuration, it is possible to identify whether the detected debris is a conductive material such as a metal material or a non-conductive material such as a resin / ceramic material.

  The fragment detection sensor according to the present invention is a fragment detection sensor that detects a fragment mixed in a fluid, and includes three electrodes. By moving at least one of the three electrodes, any one of the two electrodes is moved. Since there is provided an electrode moving mechanism for sandwiching the debris in the body and a measurement / determination means for detecting the presence / absence, size, and accumulation amount of the debris by measuring the gap between the two sandwiched electrodes. The presence / absence, size, or accumulated amount of debris mixed therein can be detected stably without being influenced by the amount of debris mixed therein.

  A first 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 mixed in the fluid to be inspected, and includes three electrodes 5A, 5B, 7 and at least one of these three electrodes 5A, 5B, 7. By measuring the gap between the two electrodes sandwiched by the electrode moving mechanism 9 that sandwiches the fragment 13 (FIG. 4) between any two electrodes by moving, the presence / absence, size, and accumulation amount of the fragment 13 are measured. And a measurement / determination means 17 for detecting any of the above. In the case of this debris detection sensor, lubricating oil is the fluid to be inspected.

  The three electrodes 5A, 5B, and 7 and the electrode moving mechanism 9 are incorporated in the sensor unit 1. This sensor unit 1 has a base member 4, and an oil passage 4 a through which lubricating oil to be inspected flows is provided through the base member 4. The oil supply pipe 2 is connected to one end of the oil path 4a, and the oil drain pipe 3 is connected to the other end of the oil path 4a. 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.

  The three electrodes 5A, 5B, and 7 are all made of a conductive material, and are arranged side by side in the middle of the oil passage 4a of the base member 4 so as to be parallel to each other in a direction perpendicular to the penetration direction of the oil passage 4a. The One of the electrodes 5A is a fixed electrode having a flat plate shape, and is fixed in an electrically insulated state to the base member 4 via an electrode fixing member 6A made of an insulating material. The fixed electrode 5A is disposed on the lower side of the base member 4 so that the surface thereof faces the oil passage 4a. The other electrode 5B is also a flat fixed electrode, and is fixed in an electrically insulated state to the base member 4 via another electrode fixing member 6B made of an insulating material. The fixed electrode 5B is disposed on the upper side of the base member 4 so that the surface thereof faces the oil passage 4a and faces the lower fixed electrode 5A. The remaining one electrode 7 includes a plate-like electrode base 7a and a penetrating body 7b extending vertically from one surface of the electrode base 7a and penetrating through the holes 19 provided in the fixed electrode 5B and the electrode fixing member 6B. It is a movable electrode having a T-shaped cross section, and the rear end of the penetrating body 7b is connected to the movable shaft 9a of the electrode moving mechanism 9, so that it can advance and retreat integrally with the movable shaft 9a. The movable electrode 7 has an electrode base 7a positioned at the center between the fixed electrodes 5A and 5B in the oil passage 4a so that each side of the electrode base 7a faces the fixed electrodes 5A and 5B. Be placed. The penetrating body 7b of the movable electrode 7 penetrating the upper fixed electrode 5B is electrically insulated from the fixed electrode 5B. By using only the penetrating body 7b as an insulating material, the fixed electrode 5B may be electrically insulated.

The electrode 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 retreat in a direction orthogonal to the penetrating direction of the oil passage 4a of the base member 4. It is being fixed to the base member 4 via. The penetrating body 7b of the movable electrode 7 is fixed to the tip of the movable shaft 9a of the electrode moving mechanism 9 through an electrode fixing member 8 made of an insulating material in an electrically insulated state. Here, an example is shown in which a linear actuator consisting of a push-pull solenoid is used as the electrode moving mechanism 9, but any type can be used as long as it can perform a linear motion. 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 a linear motion actuator is used, unlike the case of using a rotational drive source, a mechanism for converting rotation into linear motion is unnecessary, and the fragment detection sensor can be configured to be simple and compact.
When the electrode moving mechanism 9 is operated, the movable electrode 7 connected to the movable shaft 9a via the electrode fixing member 8 advances and retreats, and approaches or separates from both the fixed electrodes 5A and 5B.

The movable shaft 9a of the electrode moving mechanism 9 is urged in the advancing direction by a compression spring 12 interposed between the spring receiving member 11 fixed to the rear end portion and the actuator fixing member 10.
FIG. 1 shows a state in which the electrode moving mechanism 9 is turned on to set the first mode in which the advance of the movable shaft 9a is restricted. At this time, the movable shaft 9a is slightly retracted by compressing the compression spring 12. The movable electrode 7 is at a central position away from both the fixed electrodes 5A and 5B. On the other hand, in a state where the electrode moving mechanism 9 is not turned on, the movable electrode 7 advances to a position in contact with the lower fixed electrode 5A as shown in FIG. Since the movable electrode 7 and the fixed electrode 5A are in contact with each other and the preload is applied to the movable electrode 7 by the compression spring 12, the movable electrode 7 and the fixed electrode 5 are in contact with each other at a constant pressure. FIG. 3 shows a state in which the electrode moving mechanism 9 is turned on, and the movable shaft 9a is set to the second mode in which the movable shaft 9a is retracted upward from the state of the first mode in FIG. Retracts to a position in contact with the upper fixed electrode 5B.

  The measurement / determination unit 17 includes a capacitance measurement unit 14, a displacement sensor 16, and a determination unit 15. The capacitance measuring means 14 is a means for measuring the capacitance between the movable electrode 7 and each of the fixed electrodes 5A and 5B. The input terminals 14a and 14b of the capacitance measuring means 14 are respectively connected to the movable electrode 7 and the movable electrode 7. Connected to the fixed electrodes 5A and 5B. The displacement sensor 16 is a gap sensor that measures a gap between the movable electrode 7 and each of the fixed electrodes 5A and 5B. For example, the displacement sensor 16 is provided in a state of being embedded in the lower fixed electrode 5A. In this case, the displacement sensor 16 directly measures the gap between the movable electrode 7 and the lower fixed electrode 5A. However, the distance between the fixed electrodes 5A and 5B and the electrode base of the movable electrode 7 are measured. Since the thickness of 7a is constant, the gap between the movable electrode 7 and the upper fixed electrode 5B is also automatically calculated from the measured gap between the movable electrode 7 and the lower fixed electrode 5A.

  Here, for example, an eddy current type is used as the displacement sensor 16, but other types such as a magnetic type and an optical type may be used. The determination means 15 is a means for estimating the presence / absence of the debris 13 in the lubricating oil, the material, size, or accumulation amount of the debris 13 from the measurement value of the capacitance measurement means 14 and the measurement value of the displacement sensor 16. For example, it has a table or an arithmetic expression determination rule that defines the relationship between the measurement value and the determination result, compares the determination rule with the measurement value, and outputs the determination result. The determination unit 15 includes a conductive / nonconductive determination unit 18 that determines whether the debris 13 detected as part of the function is a conductive material or a nonconductive material.

Next, the operation for detecting the fragments from the lubricating oil mixed with the fragments made of various materials caused by wear or damage of the engine, gear box, bearing or the like using this fragment detection sensor will be described. .
As described above, when the electrode moving mechanism 9 is turned on and set to the second mode, for example, the movable shaft 9a moves backward as shown in FIG. 3 and is installed on the movable shaft 9a via the electrode fixing member 8. The moved movable electrode 7 is separated from the lower fixed electrode 5A, and the movable electrode 7 comes into contact with the upper fixed electrode 5B.

Next, as the fluid to be inspected, the lubricating oil used in the engine, gear box, bearing, etc. is passed through the oil passage 2a of the oil supply piping 2 through the oil passage 4a of the base member 4, and the oil in the drainage piping 3 Flow on path 3a. At this time, if debris 13 caused by wear or breakage of the engine, gearbox, bearing, or the like is mixed in the lubricating oil flowing through the oil passage 4a of the base member 4, the debris 13 is moved from the movable electrode 7 to the lower side. Between the fixed electrode 5A.
Under this state, when the power supply to the electrode moving mechanism 9 is stopped, the movable electrode 7 moves in the direction of approaching the lower fixed electrode 5A integrally with the movable shaft 9a by the restoring force of the compression spring 12. As shown in FIG. 4, the debris 13 is sandwiched between the movable electrode 7 and the lower fixed electrode 5A. As a result, a gap d is generated between the movable electrode 7 and the fixed electrode 5 </ b> A by the thickness of the debris 13. The displacement sensor 16 measures the gap d. At the same time, a capacitance C is formed between the two electrodes 5A and 7 by the gap d.

By the way, in general, the capacitance C between parallel plates is C = εoεrS / d (1)
It is known that That is, the capacitance C [F] is obtained by multiplying the dielectric constant εo (8.854 × 10 ⁻¹² [F / m]) in vacuum 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. When the dielectric constant εr of the lubricating oil is constant and the area S of the parallel plate is constant, the value of the capacitance C depends on the gap d between the parallel plates.
Therefore, by measuring the capacitance C between the two electrodes 5A and 7 by the capacitance measuring means 14, the value of the gap d between the electrodes 5A and 7 can be determined by a method different from the measurement by the displacement sensor 16. It can be detected, and the size and accumulation amount of the fragments 13 can also be estimated based on the value.

Here, when the sandwiched debris 13 is made of a conductive material, the two electrodes 5A and 7 are short-circuited, and therefore the gap d2 obtained from the measurement of the capacitance C is zero or a very small value. . On the other hand, the gap d1 obtained by the displacement sensor 16 is a value different from the gap d2 estimated from the measured value of the capacitance measuring means 14. In this way, it is possible to detect the difference between the two measurement results and determine whether the detected debris 13 is conductive or non-conductive. That is, the conductive / nonconductive determination unit 18 of the determination unit 15 has a function of determining whether the detected debris 13 is a conductive material or a nonconductive material,
d1 >> d2 (2)
In such a case, it is determined that the detected debris 13 is conductive. Further, when the two values d1 and d2 are close to each other and are not zero gaps, that is, d1≈d2 (≠ 0) (3)
In such a case, it is determined that the detected debris 13 is non-conductive. The determination means 15 outputs the size of the fragment 13 as a representative value detected by the displacement sensor 16.

  On the other hand, even if there is no debris 13 between the two electrodes 5A and 7, the two electrodes 5A and 7 are short-circuited, so the gap d2 obtained from the measurement of the capacitance C is zero or very small. Value. In this case, since the gap d1 obtained by the displacement sensor 16 is also a zero gap, the determination means 15 determines that there is no debris 13 from these results.

  Next, when the electrode moving mechanism 9 is turned on and set in the second mode from the state of FIG. 4, the movable shaft 9a is further retracted from the first mode as shown in FIG. And a debris 13 are sandwiched between the upper fixed electrode 5B and the upper fixed electrode 5B. As a result, a gap d is generated between the movable electrode 7 and the upper fixed electrode 5B by the thickness of the debris 13. The displacement sensor 16 measures the gap d. In this case, the displacement sensor 16 indirectly measures the gap between the movable electrode 7 and the upper fixed electrode 5B based on the gap measurement value between the lower fixed electrode 5A and the movable electrode 7. Become. At the same time, a capacitance C is formed between the two electrodes 5B and 7 by the gap d. Here, in the same manner as when the debris 13 is sandwiched between the movable electrode 7 and the lower fixed electrode 5A, the presence / absence, size, and accumulation amount of the debris 13 are detected, and the detected debris 13 It is determined whether it is conductive or non-conductive.

  FIG. 6 shows a configuration example of the capacitance measuring means 14 which is a component of the measuring / determining means 17 in the fragment detection sensor of FIG. The capacitance measuring means 14 includes 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 electrode 7 and the fixed electrodes 5A and 5B, and between the electrodes 5A and 7 and the electrodes 5B and 5B. The capacitance C between 7 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. 7 shows another configuration example of the capacitance measuring means 14 which is a constituent element of the measuring / determining means 17 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. The capacitance C between 5A and 7 and between the electrodes 5B 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) (4)
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 electrodes 5A and 7 and between the electrodes 5B and 7.

  FIG. 8 shows still another configuration example of the capacitance measuring unit 14 which is a component of the measuring / determining unit 17 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 means 41 measures the voltage measurement means 46 for monitoring the charge / discharge voltage in the charge / discharge means 40 and the time until the voltage monitored by the voltage measurement means 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 to be measured is replaced with the capacitance C between the electrodes 5A and 7 and between the electrodes 5B and 7 so that the capacitance C is estimated.

As described above, in the debris detection sensor of this embodiment, at least one electrode (movable electrode) 7 among the three electrodes 5A, 5B, 7 is moved by the electrode moving mechanism 9, so that any two electrodes (lower The debris 13 is sandwiched between the fixed electrode 5A on the side and the movable electrode 7 and between the fixed electrode 5B on the upper side and the movable electrode 7), and the gap between the two sandwiched electrodes is measured by the measurement / determination means 17 Therefore, since the presence or absence, the size, and the accumulation amount of the debris 13 is detected, the probability that the debris 13 is sandwiched between the two electrodes increases, and the presence or absence of the debris 13 mixed in the lubricating oil or The size or accumulated amount can be detected stably without being influenced by the amount of mixed pieces 13.
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.

  In this embodiment, of the three electrodes 5A, 5B, 7, the upper two electrodes (the fixed electrode 5B and the movable electrode 7) and the lower two electrodes (the movable electrode 7 and the fixed electrode 5A) Gap measuring means (displacement sensor 16 and capacitance measuring means 14) for measuring the gap are provided between them, and an electrode moving mechanism (linear actuator) 9 is provided between the upper two electrodes 5B and 7 and the lower two electrodes. Since the central electrode (movable electrode) 7 is moved up and down so that the debris 13 is sandwiched between the electrodes 7 and 5A, the detection operation is performed at both ends of one stroke of the central electrode (movable electrode) 7. As a result, the efficiency of the detection operation can be increased.

  In this embodiment, an electrode moving mechanism (linear motion actuator) 9 for operating the central electrode (movable electrode) 7 is installed outside the flow path (oil path) 4a through which the fluid to be inspected (lubricating oil) flows. In addition, since the movable electrode 7 is moved through the through body 7b penetrating the hole 19 provided in one of the two fixed electrodes 5A and 5B, the three electrodes 5A, 5B and 7 are compact. Can be placed.

  Further, in this embodiment, the capacitance between the fixed electrode 5A and the movable electrode 7 and between the fixed electrode 5B and the movable electrode 7 is measured by the capacitance measuring means 14, and between these two electrodes. The gap is measured by the displacement sensor 16 and has a conductive / nonconductive determination unit 18 for determining the conductivity and nonconductive of the fragments 13 from the outputs of these two types of sensors 14 and 16. It is possible to identify whether the broken piece 13 is a conductive material such as a metal material or a non-conductive material such as a resin / ceramic material.

  The means for measuring the gap between the two electrodes 5 and 7 is not limited to the case where the capacitance measuring means 14 and the displacement sensor 16 are used together as in the embodiment, but the capacitance measuring means. Only 14 may be used, or only the displacement sensor 16 may be used. When only the capacitance measuring means 14 is used, if a coating layer made of an insulating material is provided on at least one of the two electrodes facing each other, the debris 13 sandwiched between the two electrodes is electrically conductive. Since even if it consists of a conductive material, between two electrodes does not short-circuit, regardless of whether the debris 13 is a conductive material or a non-conductive material, the capacitance between the two electrodes can be measured correctly, Presence / absence, size, and accumulation amount of the fragments 13 can be accurately detected.

  FIG. 9 shows another embodiment of the fragment detection sensor of the present invention. In this embodiment, the displacement sensor 16 in the embodiment shown in FIG. 1 is provided at a position facing the rear end of the movable shaft 9 a in the actuator fixing member 10.

  In the case of this embodiment, the displacement sensor 16 measures the amount of displacement of the movable shaft 9a. However, since the movable electrode 7 is connected to the movable shaft 9a via the electrode fixing member 8, the displacement of the movable shaft 9a. From the amount of displacement, the gap d between the fixed electrode 5A and the movable electrode 7 and the gap d between the fixed electrode 5B and the movable electrode 7 can be detected.

  FIG. 10 shows still 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. It is possible to estimate the state of the lubricating oil from the recorded change history of numerical values and output information such as an increasing tendency of dust and debris. The capacitance measuring means 14 may use any configuration shown in FIGS.

It is a schematic block diagram which shows the state in the 1st mode at the time of power activation of the fragment detection sensor which concerns on 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 a schematic block diagram which shows the state in the 2nd mode at the time of power activation of the fragment detection sensor. It is explanatory drawing of the detection operation of the same fragment detection sensor. It is another explanatory view of the detection operation of the 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 explanatory drawing of the detection operation | movement of the fragment detection sensor which concerns on other embodiment of this invention. It is explanatory drawing of the detection operation | movement of the fragment detection sensor which concerns on further another embodiment of this invention.

Explanation of symbols

4a ... oil passages 5A, 5B ... fixed electrode 7 ... movable electrode 7b ... penetrating body 9 ... electrode moving mechanism 13 ... fragment 14 ... capacitance measuring means 15 ... judging means 16 ... displacement sensor 17 ... measuring / judging means 18 ... conductive -Conductivity / non-conductivity discrimination part 19 ... hole

Claims (5)

  A debris detection sensor for detecting debris mixed in a fluid, comprising three electrodes, and moving at least one of these three electrodes to sandwich the debris between any two electrodes A fragment detection sensor provided with a mechanism and measurement / determination means for detecting any of the presence / absence, size, and accumulation amount of the fragment by measuring a gap between two sandwiched electrodes.   2. The gap measuring means for measuring a gap is provided between the upper two electrodes and the lower two electrodes of the three electrodes, respectively, and the electrode moving mechanism is provided between the upper two electrodes. And a fragment detection sensor for moving the center electrode up and down so that the fragment is sandwiched between the two lower electrodes.   The electrode movement mechanism for operating the center electrode is installed outside the flow path for flowing the fluid, and the electrode movement mechanism is provided on one of the two electrodes on the fixed side. A debris detection sensor for moving a movable electrode through a penetrating body penetrating a hole.   2. The measurement / judgment means according to claim 1, wherein the measurement / judgment means includes a capacitance measurement means for measuring a capacitance between two electrodes sandwiching a debris, and a gap between the two electrodes from an output of the capacitance measurement means. A debris detection sensor comprising determination means for estimating the size of the debris. 5. The measurement / judgment means according to claim 4, further comprising a displacement sensor that measures a gap between two electrodes sandwiching the debris, and from the output of the capacitance measurement means and the output of the displacement sensor, A debris detection sensor having a conductive / non-conductive discriminating portion for discriminating between conductivity and non-conductive of a fragment sandwiched between two electrodes.

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