JP2008249387A - Fragment detection sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fragment detection sensor capable of detecting fragments with high detection probability, even when a trace amount of fragments is intermingled into fluid. <P>SOLUTION: The fragment detection sensor, which is a means for detecting fragments intermingled into fluid, includes a plurality of plates 5 arranged in parallel in the state where a clearance is secured mutually by interposition of a spring 6. The sensor also includes a plate moving mechanism 9 capable of sandwiching fragments between the plurality of plates 5, 5 by moving at least one plate among the plurality of plates 5 in the plate arrangement direction, and a measurement and determination means 14. The measurement and determination means 14 detects existence, the size or the accumulation amount of the fragments by measuring the distance between the plates 5, 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a debris detection sensor that detects debris 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 that metal fragments or metal particles generated by wear or damage of engines, transmissions, bearings, etc. are 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 material, 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.

  In order to solve such a problem, two flat plate electrodes face each other in a fluid, and at least one of the two flat plate electrodes is moved in the facing direction, whereby a piece is sandwiched between the two flat plate electrodes. In this case, a configuration in which a change in the distance between the two plate electrodes at this time is detected by a displacement sensor, a change in capacitance, or the like can be considered.

  However, in the case of the above-described configuration, since one piece of detection is performed by operating the plate electrode once, there is a problem that the detection probability is low when detecting a small amount of pieces.

  An object of the present invention is to provide a debris detection sensor capable of detecting debris with a high detection probability even if a small amount of debris is mixed in a fluid.

The debris detection sensor according to the present invention is a means for detecting debris mixed in the fluid, and includes a plurality of flat plates arranged in parallel with a gap secured by the interposition of springs, and at least one of the plurality of flat plates. By measuring the distance of the gap between the flat plate moving mechanism that sandwiches the pieces between a plurality of flat plates by moving two flat plates in the plate arrangement direction, the presence or absence of the pieces, the size, or the accumulated amount Measuring / determining means for detecting.
According to this configuration, at least one of the plurality of flat plates arranged side by side with springs interposed therebetween is moved in the plate arrangement direction, and the distance between the gap plates is measured by the measuring / judging means. Since the measurement is performed and the presence / absence, size, or accumulation amount of debris is detected from the measured value, the state of the debris mixed in the fluid can be estimated. In particular, a plurality of flat plates are arranged side by side with springs interposed between them, and one of them is moved in the flat plate alignment direction so that the pieces are sandwiched between the flat plates. Therefore, even if a small amount of debris is mixed in the fluid, the probability that the debris can be detected by one detection operation can be increased.
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 this invention, the measurement / determination means may measure the distance of the gap between the flat plates with a displacement sensor.

  In the present invention, each flat plate may be a flat plate electrode, and the measurement / determination means may measure a gap distance between the flat plate electrodes by a capacitance. According to the capacitance, the gap distance between the flat plates can be accurately measured with a simple configuration.

  In the present invention, an insulating coating may be formed on the surface of each flat plate. Thus, by covering the surface of the flat plate with the insulating film, even when conductive fragments are sandwiched between the flat plate electrodes, the size can be detected. Further, even when a part of the flat plate electrodes arranged in parallel is brought into a contact state due to the inclination of the flat plate electrodes, a change in capacitance can be detected.

  In the present invention, electrical wiring may be connected to the plate electrodes located at both ends in the plate alignment direction, and the measurement / determination means may measure a series capacitance to detect a gap change.

  In the present invention, electrical wiring may be connected so that the plate electrodes alternately become measurement electrodes, and the measurement / determination means may be configured to measure a parallel capacitance and detect a gap change. .

  In the present invention, the flat plate moving mechanism may move the flat plate using an electromagnetic, hydraulic or pneumatic linear actuator as a drive source. 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.

  The debris detection sensor according to the present invention is a means for detecting debris mixed in the fluid, and includes a plurality of flat plates arranged in parallel with a gap secured by the interposition of springs, and at least one of the plurality of flat plates. By measuring the distance of the gap between the flat plate moving mechanism that sandwiches the pieces between a plurality of flat plates by moving two flat plates in the plate arrangement direction, the presence or absence of the pieces, the size, or the accumulated amount Therefore, even if the amount of fragments mixed in the fluid is very small, it is possible to detect the fragments with a high detection probability.

  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 fragment detection sensor is means for detecting fragments mixed in the fluid to be inspected, and is arranged side by side so as to overlap each other with a gap secured by the interposition of springs 6 as shown in FIG. A plurality of flat plates 5 are provided. Further, by moving at least one of the plurality of flat plates 5 in the flat plate arrangement direction, a flat plate moving mechanism 9 that sandwiches the fragments 13 (FIG. 4) between the plurality of flat plates 5 and 5, and the flat plates 5 and 5. Measurement / determination means 17 for detecting the presence / absence, size, or accumulation amount of the debris 13 by measuring the gap distance between them. In the case of this debris detection sensor, lubricating oil is the fluid to be inspected.

  The plurality of flat plates 5 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.

  Each of the flat plates 5 has a disk shape, for example, as shown in a plan view and a perspective view in FIGS. 2 (A) and 2 (B), and three concave portions 5a are equally arranged on the upper surface in the circumferential direction. The spring 6 is fixed in each of the recesses 5a. The spring 6 is made of, for example, a leaf spring, and is fixed in a state in which a part thereof protrudes from the upper surface of the flat plate 5. The flat plate 5 at the lowest position among the flat plates 5 has a guide shaft 5b (FIG. 1) protruding upward from the central portion thereof. Moreover, the flat plate 5 except the flat plate 5 of the lowest position among each flat plate 5 has the guide hole 5c which penetrates the said guide shaft 5b in the center part like FIG. When the guide shaft 5b of the lowermost flat plate 5 is passed through the guide hole 5c of the other flat plate 5 so as to have a vertically upward posture as shown in FIG. A plurality of flat plates 5 are arranged so as to overlap each other.

  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. The flat plates 5 arranged side by side so as to overlap vertically are connected to the distal end portion of the movable shaft 9a of the linear actuator 9 through the guide shaft 5b of the lowermost flat plate 5 passing through the base member 4. Thus, the base member 4 is disposed in the oil passage 4a. 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 lowermost flat plate 5 connected to the movable shaft 9a advances and retreats.

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 9a is retracted by compressing the compression spring 12, and the lowermost flat plate 5 is pulled upward. . In this state, the spring 6 interposed between the flat plates 5, 5 is compressed and fits in the recess 5 b, the surfaces of the flat plates 5 come into contact with each other, and the uppermost flat plate 5 is pushed against the inner wall surface of the base member 4. Hit. In this case, if the strength of the spring 6 of the uppermost flat plate 5 is set to be the strongest, the flat plates 5 and 5 can be kept in contact with each other even if the guide shaft 5b is slightly inclined. .
On the other hand, in the state where the power is not supplied to the linear actuator 9, the flat plate 5 at the lowest position advances downward due to the restoring force of the compression spring 12 compressed when the power is turned on as shown in FIG. In this state, since the spring 6 interposed between the flat plates 5 and 5 is released from compression, a clearance is secured between the flat plates 5 and 5 by the restoring force, and the lubricating oil passes through the gap.

  The measurement / determination unit 14 includes a displacement sensor 15 and a determination unit 17. The displacement sensor 15 is a gap sensor that measures the gap between the flat plates 5 and 5 arranged side by side. For example, the displacement sensor 15 is embedded in a position facing the flat plate 5 on the inner wall surface of the oil passage 4 a of the base member 4. . Here, for example, an eddy current type is used as the displacement sensor 15, but another type such as a magnetic type or an optical type may be used. The determination means 17 is a means for estimating the presence, size, or accumulation amount of the debris 13 (FIG. 4) in the lubricating oil from the measurement value of the displacement sensor 15, and for example, the relationship between the measurement value and the determination result is defined. It has a determination rule for a table or an arithmetic expression, and compares the determination rule with a measured value and outputs a determination result.

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 lowermost flat plate 5 connected to the movable shaft 9a by the guide shaft 5b is in the upper position. Be pulled. As a result, the spring 6 interposed between the flat plates 5 and 5 is compressed and fit in the concave portion 5a of the flat plate 5, and the surface between the flat plates 5 and 5 is brought into contact. At this time, the displacement sensor 15 measures a distance d0 from the installation position to the lower surface of the lowermost flat plate 5.

  Next, when the power supply to the linear motion actuator 9 is stopped, the lowermost flat plate 5 advances in a direction approaching the displacement sensor 15 integrally with the movable shaft 9 a by the restoring force of the compression spring 12. Thereby, the spring 6 interposed between the flat plates 5 and 5 is released from compression, and a gap is generated between the flat plates 5 and 5 as shown in FIG. Under this state, as a fluid to be inspected, lubricating oil used in the engine, gearbox, bearing, etc. is drained from the oil passage 2a of the oil supply pipe 2 through the oil passage 4a of the base member 4. It flows in the oil passage 3a of the pipe 3.

  Next, when the power is reapplied to the linear actuator 9, the movable shaft 9a moves backward as in the case of FIG. 1, and the lowermost flat plate 5 connected to the movable shaft 9a is pulled to the upper position. At this time, as shown in FIG. 4, if the fragments 13 are interposed between some of the gaps between the flat plates 5, 5, the flat plates 5, 5 with the fragments 13 are kept in a non-contact state. For this reason, the distance d from the installation position of the displacement sensor 15 to the lower surface of the flat plate 5 at the lowermost position is shorter than the distance d0 in the case of FIG. The displacement sensor 15 measures the distance d at this time. That is, the displacement sensor 15 indirectly measures the gap amount due to the interposition of the debris 13 by measuring the distance d0 when the debris 13 is not present and the distance d when the debris 13 are present. 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 means 17 based on the measured value of the displacement sensor 15.

Thus, in the fragment detection sensor of this embodiment, at least one flat plate 5 (here, the flat plate at the lowest position) among the plurality of flat plates 5 arranged in parallel with a gap secured by the spring 6 interposed therebetween. Are moved in the plate alignment direction, the distance of the gap between the plates 5 and 5 is measured by the displacement sensor 15, and the presence / absence, size, or accumulation amount of the debris 13 is determined by the determination means 17 from the measured value of the displacement sensor 15. Therefore, the state of the fragments 13 mixed in the lubricating oil can be estimated. In particular, a plurality of flat plates 5 are arranged side by side with springs 6 between them, and one of them is moved in the flat plate alignment direction so that the fragments 13 are sandwiched between the flat plates 5 and 5. Therefore, the flat plate area for detecting the fragments 13 can be increased, and the probability that the fragments 13 can be detected by one detection operation can be increased even if the amount of the fragments 13 mixed in the lubricating oil is very small. .
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.

  5 to 12 show another embodiment of the debris detection sensor of the present invention. In this embodiment, in the embodiment shown in FIGS. 1 to 4, each flat plate 5 is a flat plate electrode, and the measurement / determination means 14 is composed of a capacitance measurement means 16 and a determination means 17. That is, in this embodiment, the gap between the plate electrodes 5 and 5 is measured by electrostatic capacity. A measuring instrument such as a capacitance meter can be used for the capacitance measuring means 16. In this case, the surface of each plate electrode 5 is covered with an insulating coating. For example, aluminum is used as the material of the plate electrode 5 and the surface thereof is alumite treated to provide an insulating coating. Thus, by covering the surface of the flat electrode 5 with the insulating film, even when the conductive debris 13 is sandwiched between the flat electrodes 5 and 5, the size can be detected. Further, even when a part of the flat plate electrodes 5 and 5 are arranged in contact with each other due to the inclination of the flat plate electrode 5, a change in capacitance can be detected. In addition, a conductive material can be used as the spring 6 interposed between the plate electrodes 5 and 5.

  Further, in this embodiment, the guide shaft 5 b of the flat plate electrode 5 at the lowest position and the movable shaft 9 a of the linear actuator 9 are connected via an insulating member 8. Further, of the inner wall surface of the oil passage 4a of the base member 4, for example, insulating members 7A and 7B are disposed at a portion where the uppermost plate electrode 5 contacts or a portion where the lowermost plate electrode 5 faces. .

  The electrostatic capacity measuring means 16 measures the electrostatic capacity between the uppermost plate electrode 5 and the lowermost plate electrode 5 among the plurality of flat plate electrodes 5 arranged in parallel vertically. One input terminal of the capacitance measuring means 16 is connected to the uppermost plate electrode 5, and the other input terminal is connected to the lowermost plate electrode 5. The intermediate plate electrode 5 is in a floating state. The determination unit 17 estimates the state of the debris 13 in the lubricant oil from the measurement value of the capacitance measurement unit 16. Other configurations are the same as those of the previous embodiment shown in FIGS.

  An equivalent circuit of the plate electrode 5 is shown in FIG. 6A shows the case where the flat plate electrodes 5 are in contact with each other (see FIG. 1), and FIG. 6B shows the case where the fragments 13 are sandwiched between some flat plate electrodes 5 and 5, respectively. Yes. In this equivalent circuit, as shown in FIG. 6A, the capacitance Cs due to the insulating film of each plate electrode 5 is connected in series between both input terminals of the capacitance measuring means 16.

As shown in FIG. 6B, when the debris 13 is sandwiched between some of the flat plate electrodes 5 and 5, the interelectrode capacitance becomes αCs (α <1), which is detected as a change in the overall capacitance. . That is, in the state of FIG. 6 (A) where the debris 13 is not sandwiched, the overall capacitance C is
1 / C = 1 / Cs + 1 / Cs +... = N / Cs (1)
(Where n is the number between the flat plate electrodes 5 and 5), in the state of FIG. 6B in which the fragments 13 are sandwiched,
1 / C = 1 / Cs + 1 / αCs + 1 / Cs... = (N-1) / Cs + 1 / αCs (2) As shown in FIG. 5, when the fragments 13 are interposed between the plurality of plate electrodes 5, 5, it is assumed that similar fragments 13 are interposed between the k plate electrodes 5, 5. ,
1 / C = (n−k) / Cs + k / αCs (3)
Will change as follows. Although it is difficult to strictly identify the size and number of the pieces 13, when a small amount of pieces 13 are mixed, the pieces 13 are sandwiched between the flat plate electrodes 5 and 5 in one detection operation. There are many states, and the approximate size of the shard 13 can be estimated from the above equation (2).

  FIG. 7 shows another configuration example of the plate electrode 5 in the embodiment of FIG. In this configuration example, as shown in FIG. 7A, the flat plate electrodes 5 that are arranged side by side vertically are arranged so that the installation surfaces of the respective springs 6 face downward, and the flat plate electrode 5 at the uppermost position is arranged. A guide shaft 5b is provided integrally. The guide shaft 5b protrudes up and down, its lower end is supported on the inner wall surface of the oil passage 4a of the base member 4 via the insulating member 7B, and the upper end is movable of the linear actuator 9 as shown in FIG. The shaft 9a is connected via an insulating member 8. When the uppermost plate electrode 5 is pushed down by the linear actuator 9, the spring 6 between the plate electrodes 5 and 5 is compressed, the plate electrodes 5 and 5 are in contact with each other, and the lowermost plate electrode 5 is It is pressed against the insulating member 7B. Further, when the uppermost plate electrode 5 is pulled up by the linear actuator 9, a gap is secured between the plate electrodes 5 and 5 by the double force of the spring 6 as shown in FIG.

  Also in this case, the surface of each flat plate electrode 5 is covered with an insulating film, and the electrostatic capacity measuring means 16 is placed on the uppermost flat plate electrode 5 and the lowermost flat plate electrode 5 as shown in FIG. Each input terminal is connected. The equivalent circuit of the capacitance in the plate electrode 5 in this connection configuration is the same as that in the case of FIG.

The connection with the capacitance measuring means 16 may be as shown in FIG. In the connection configuration of FIG. 8, one input terminal of the capacitance measuring means 16 is connected from the uppermost flat plate electrode 5 to every other flat plate electrode 5, and the other input terminal is extended to the remaining flat plate electrodes 5. Connected. As shown in FIG. 9, the equivalent circuit of the capacitance in the plate electrode 5 in the case of this connection configuration is formed between the input terminals of the capacitance measuring means 16 and the capacitance Cs due to the insulating film of each plate electrode 5. Are connected in parallel.
In this case, when the fragments 13 are sandwiched between the k plate electrodes 5 and 5, the entire capacitance C is
C = (n−k) Cs + αkCs (4)
It becomes. Although the change amount of the detection capacitance value is relatively small, since the debris 13 is captured with a wide detection area, detection with an increased detection probability is possible.

  FIG. 10 shows a configuration example of the capacitance measuring means 16 which is a component of the measuring / determining means 14 in the fragment detection sensor of FIG. The capacitance measuring means 16 is composed of an oscillator 20 and a current measuring means 21 connected in series. An alternating current is passed from the oscillator 20 to the uppermost plate electrode 5 and the lowermost plate electrode 5, and both the plate electrodes 5. The capacitance C between 5 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. 11 shows another configuration example of the capacitance measuring means 16 which is a component of the measuring / determining means 14 in the fragment detection sensor of FIG. The capacitance measuring means 16 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 the electrodes 5 and 5 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) (5)
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 plate electrodes 5 and 5.

  FIG. 12 shows still another configuration example of the capacitance measuring means 16 which is a constituent element of the measuring / determining means 14 in the fragment detection sensor of FIG. The capacitance measuring unit 16 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 a transient phenomenon in the repeated 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 flat plate electrodes 5 and 5, so that the capacitance C is estimated.

  FIG. 13 shows still another embodiment of the fragment detection sensor of the present invention. In this embodiment, in the embodiment shown in FIG. 5, a recording means 50 is added to the next stage of the judging means 17 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 16 shown in FIGS. 10 to 12 may be used. Note that the determination unit 17 may determine that a failure has occurred because the value of the variation in capacitance measured by the capacitance measurement unit 16 exceeds a predetermined threshold.

It is a schematic block diagram at the time of power activation of the fragment detection sensor which concerns on 1st Embodiment of this invention. (A) is a top view of the flat plate in the fragment detection sensor, (B) is a perspective view of the flat plate. 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 | movement of the fragment detection sensor which concerns on other embodiment of this invention. (A) is an equivalent circuit in the state in which the fragment | piece of the flat plate electrode in the same fragment detection sensor is not pinched | interposed, (B) is an equivalent circuit in the state which has pinched the fragment | piece of the flat plate electrode. (A) is sectional drawing of the other structural example of a flat plate electrode, (B) is a block diagram which shows the connection state of the electrostatic capacitance measurement means to the flat plate electrode. It is a block diagram which shows the other connection state of the electrostatic capacitance measurement means to the same plate electrode. FIG. 9 is an equivalent circuit of a plate electrode in the connection configuration example of FIG. 8. FIG. It is a circuit diagram which shows the other structural example of the electrostatic capacitance measurement means in the fragment detection sensor of FIG. 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 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 further another embodiment of this invention.

Explanation of symbols

5 ... Flat plate 6 ... Spring 9 ... Linear motion actuator (flat plate moving mechanism)
13 ... Fragment 14 ... Measurement / determination means 15 ... Displacement sensor 16 ... Capacitance measurement means 17 ... Determination means

Claims (7)

  A means for detecting debris mixed in the fluid, and a plurality of flat plates arranged in parallel with each other with a gap interposed by a spring, and at least one of the plurality of flat plates is moved in the plate arrangement direction. A flat plate moving mechanism for sandwiching the fragments between a plurality of flat plates, and a measuring / determining means for detecting the presence or absence, the size, or the accumulation amount of the fragments by measuring the distance of the gap between the flat plates. A debris detection sensor.   2. The debris detection sensor according to claim 1, wherein the measurement / determination means measures a gap distance between the flat plates with a displacement sensor.   2. The fragment detection sensor according to claim 1, wherein each of the flat plates is a flat plate electrode, and the measurement / determination means measures a gap distance between the flat plate electrodes by a capacitance.   4. A debris detection sensor according to claim 3, wherein an insulating film is formed on the surface of each flat plate.   4. A fragment detection sensor according to claim 3, wherein electrical wiring is connected to the plate electrodes located at both ends of the plate arrangement direction, and the measurement / determination means detects a change in gap by measuring a series capacitance.   4. Debris detection according to claim 3, wherein electrical wiring is connected so that the plate electrodes alternately become measurement electrodes, and the measurement / judgment means is configured to detect a gap change by measuring parallel capacitance. Sensor.   7. A fragment detection sensor according to claim 1, wherein the flat plate moving mechanism moves the flat plate using an electromagnetic, hydraulic or pneumatic linear actuator as a drive source.

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