JP2010014520A - Device for detecting metal particles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine abnormality in hydraulic equipment by attraction of metal particles. <P>SOLUTION: The metal particle detecting device comprises a plurality of electrode 11-15, arranged at a sensor body 2 with a space between each other and are immersed in oil; an attracting means 17 for attracting metal particles mixed in the oil to the electrodes 11-15; an electrical circuit formed, such that the electrodes 11-15 short-circuit with each other due to metal particles attracted by the attracting means 17; a detecting means 26 for detecting a voltage value V, which varies due to short circuit between the electrodes 11-15; and a determining means 29 for determining whether the degree of increase in metal particles is abnormal, based on a relationship between the voltage value v detected by the detecting means 26 and time Δti, Ti. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a metal particle detection device that detects metal particles present in oil such as hydraulic oil or lubricating oil.

  Conventionally, a device has been known in which metal particles in oil are adsorbed by a magnetic force to a plurality of electrodes provided at the tip of a sensor, and metal particles in oil are detected using resistance change between the electrodes. (For example, refer to Patent Document 1). In the device described in Patent Document 1, a magnet is provided at an end of a sensor, and a plurality of rod-shaped electrodes are disposed around the magnet via an insulator. Then, the electrodes are short-circuited by the metal particles adsorbed by the magnetic force, and the degree of oil contamination is detected from the number of short-circuits.

JP 2005-274486 A

  However, for example, even when the hydraulic equipment is operating in a normal state, metal particles may be mixed into the oil due to normal wear. For this reason, it is difficult to determine whether or not an abnormality has occurred in the hydraulic device only by detecting the number of short circuits as in the device described in Patent Document 1.

A metal particle detection device according to the present invention includes a plurality of electrodes that are disposed apart from each other and are immersed in oil, an adsorption unit that adsorbs metal particles mixed in oil to the electrode, and an adsorption unit. An electrical circuit configured so that the electrodes are short-circuited by the adsorbed metal particles, a detection unit that detects a voltage value that changes due to a short-circuit between the electrodes, and a relationship between the voltage value detected by the detection unit and time Storage means for storing.
Further, the metal particle detection device according to the present invention includes a plurality of electrodes that are disposed apart from each other in the sensor body and are immersed in oil, an adsorption unit that adsorbs metal particles mixed in the oil to the electrode, and an adsorption unit The electrical circuit configured to short-circuit the electrodes by the metal particles adsorbed by the electrode, the detection means for detecting the voltage value that changes due to the short-circuit between the electrodes, the relationship between the voltage value detected by the detection means and time And determining means for determining whether or not the degree of increase of the metal particles is abnormal.

  According to the present invention, based on the relationship between the detection value of the voltage that changes due to a short circuit between the electrodes and the time, it is determined whether or not the degree of increase of the metal particles is abnormal, so that the abnormality of the hydraulic equipment The occurrence can be accurately determined.

Hereinafter, an embodiment of a metal particle detection device according to the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing an attached state of the metal particle detection device according to the present embodiment. The metal particle detector is attached to an oil pipe 1 through which, for example, hydraulic oil or lubricating oil passes, and detects metal particles in the pipe. In the example of FIG. 1, a screw portion 3 is provided on the outer peripheral surface of the tip portion of the sensor body 2, and the sensor body 2 is attached to the pipe 1 via the screw portion 3. The front end portion (sensor portion 4) of the sensor body 2 projects inward from the inner wall surface of the pipe 1 and is immersed in oil in the pipe. Reference numeral 5 denotes a sealing O-ring. A hydraulic device such as a hydraulic pump or a hydraulic motor is connected to the pipe 1.

  2 is a cross-sectional view (a cross-sectional view taken along the line II-II in FIG. 3) of the sensor unit 4 of the metal particle detection device according to the first embodiment, and FIG. It is a top view (arrow III figure of FIG. 1). FIG. 2 also shows an electric circuit of the metal particle detection device. A round bar-shaped center electrode 11 is provided at the center of the sensor body 2 (center 3 of the screw portion), and a plurality of (four in the figure) cylinders around the center electrode 11 are provided around the center electrode 11. Shaped ring-shaped electrodes 12 to 15 are provided concentrically. The gaps w1 to w4 between the adjacent electrodes 11 to 15 are gradually increased toward the outer side in the radial direction (w1 <w2 <w3 <w4).

  The center electrode 11 and the ring-shaped electrodes 12 to 15 are each made of a conductor, and these are fixed to the insulator 16 in a state of being separated from each other. The tip portions of the electrodes 11 to 15 protrude from the surface of the insulator 16 by a predetermined amount, and the positions of the tip portions are parallel to the oil flow. A magnet 17 (for example, a permanent magnet) is provided inside the sensor body 2 in contact with the electrodes 11 to 15, and metal particles in the pipe 1 can be attracted to the surface of the sensor unit 4 (insulator 16) by magnetic force. ing.

  As shown in FIG. 2, a lead wire 31, a resistor 21, a lead wire 33, a center electrode 11, resistors 22 to 25, and a lead wire 32 are connected to the power source 27 in series. Further, the ring-shaped electrode 12 is connected between the resistor 22 and the resistor 23 via a conducting wire 35, and the ring-shaped electrode 13 is connected between the resistor 23 and the resistor 24 via a conducting wire 36, The ring-shaped electrode 14 is connected between the resistor 24 and the resistor 25 via a conducting wire 37, and the ring-shaped electrode 15 is connected between the resistor 25 and the power source 27. When the electrodes 11 to 15 are short-circuited due to the adsorption of the metal particles, a circuit parallel to the resistors 22 to 25 is formed.

  A voltage detector 26 is connected between the conducting wire 34 and the conducting wire 32, and the voltage V of the resistors 22 to 25 divided by the resistor 21 is detected by the voltage detector 26. A recording device 28 is connected to the voltage detector 26, and a determination device 29 is connected to the recording device 28. The recording device 28 records the relationship between the voltage V detected by the voltage detector 26 and time. Based on this voltage detection value, the determination device 29 determines whether or not the degree of metal particle adsorption is abnormal, as will be described later.

  The resistors 21 to 25 are provided in the sensor body 2, and the power source 27, the voltage detector 26, the recording device 28, and the determination device 29 are provided in the measuring device 30. The sensor body 2 and the measuring device 30 are connected by conducting wires 31, 32, 34. The measuring device 30 is also provided with a display device (not shown), and displays the change in the voltage V.

Here, assuming that the voltage of the power source 27 is V0, the resistance value of the resistor 21 is R0, and the resistance between the conducting wires 32 and 33 is R, the detection value V by the voltage detector 26 is as follows.
V = V0 · R / (R0 + R)
At this time, if metal particles are not adsorbed on the surface of the sensor unit 4, the electrodes 11 to 15 are not short-circuited, and currents flow in series in the resistors 21 to 25, respectively. Therefore, if the resistance values of the resistors 22 to 25 are R1 to R4, respectively, R = R1 + R2 + R3 + R4, and V = V0 · (R1 + R2 + R3 + R4) / (R0 + R1 + R2 + R3 + R4). Here, the resistance values R1 to R4 of the resistors 22 to 25 are set to R1>R2>R3> R4.

  On the other hand, when metal particles are adsorbed to the sensor unit 4 by magnetic force, the electrodes 11 to 15 are short-circuited via the metal particles. When the electrodes 11 to 15 are short-circuited, current flows between the electrodes 11 to 15, so that the overall resistance value R changes and the detection value V of the voltage detector 26 also changes. Thereby, it can be detected that the metal particles are adsorbed on the sensor unit 4.

  In this case, since the gaps w1 to w4 between the electrodes 11 to 15 are the smallest in the center, the electrodes 11 to 15 are short-circuited in order from the center to the outside in the radial direction, and the resistance value R gradually changes. For example, the detection voltage V changes as shown in FIG. That is, when the electrodes 11 and 12 are short-circuited at time t1, the voltage changes from V0 to V1 (<V0), and when the electrodes 12 and 13 are short-circuited at time t2, the voltage becomes V2 (<V1). , 14 is short-circuited, the voltage is V3 (<V2), and when the electrodes 14 and 15 are short-circuited at time t4, the voltage is V4 (<V3). Here, the time required from when the electrodes are short-circuited until the next electrode is short-circuited, that is, t1-t0, t2-t1, t3-t2, and t4-t3 is set to Δt1 to Δt4, respectively.

  By the way, the amount of metal particles contained in the pipe 1 increases due to the use of hydraulic equipment connected to the pipe 1. In this case, even if the hydraulic equipment is in a normal state, the amount of metal particles increases due to normal wear, so that a short circuit between the electrodes 11 to 15 occurs. If the standard time required for short-circuiting between the electrodes 11 to 15 due to normal wear of the hydraulic equipment (hereinafter referred to as standard elapsed time) is T1 to T4, and Δt1 to Δt4 are equal to or greater than the standard elapsed time T1 to T4, It is estimated that metal particles increase due to normal wear of hydraulic equipment.

  On the other hand, if Δt1 to Δt4 are shorter than the reference times T1 to T4, it is estimated that the amount of metal particles has rapidly increased due to some abnormality in the hydraulic equipment. In consideration of this point, in the present embodiment, the determination device 29 determines abnormality of the hydraulic equipment as follows. The standard elapsed times T1 to T4 are values determined by the shape of the sensor unit 4 and the use conditions (oil flow rate, etc.) of the oil, are obtained by experiments and analysis, and are stored in advance in a memory or the like.

  FIG. 5 is a flowchart illustrating an example of processing in the determination device 29 configured by a CPU or the like. The process shown in this flowchart is started by operating the reset switch after the sensor unit 4 has no metal particles attached, for example, after replacing the sensor with a new one. In step S1, a variable n is set to 1 and s is set to 0 as initial conditions. Note that n increases by 1 each time a short circuit between electrodes is detected, and s increases by 1 each time an abnormality is detected. In step S2, predetermined standard elapsed times T1 to T4 are read.

  In step S3, the magnitude of the detected value V of the voltage and the calculated value (R · V0 / (R0 + R)) is determined. Note that R is represented by ΣRi (i = n to 4). In this case, n is 1 when there is no short circuit between the electrodes 11 to 15, n is 2 when the electrodes 11 and 12 are short-circuited, n is 3 when the electrodes 11 to 13 are short-circuited, If n is set to 4 when the electrodes 11 to 14 are short-circuited, the detected voltage value V is equal to the calculated value, and step S3 is affirmed. The voltage detection value V is compared with the calculated value until step S3 is negative.

  On the other hand, when n is set to 1, when the electrodes 11 and 12 are short-circuited, when n is set to 2 and when the electrodes 11 to 13 are short-circuited, n is set to 3. Sometimes, when the electrodes 11 to 14 are short-circuited, and when n is set to 4 and the electrodes 11 to 14 are short-circuited, the detected value V is smaller than the calculated value. In this case, step S3 is denied and the process proceeds to step S4.

  In step S4, the time required until the process in step S3 is denied, that is, Δt1 to Δt4 in FIG. 4 is stored. In step S5, it is determined whether or not the ratio of the elapsed time Δtn to the corresponding standard elapsed time Tn is 1 or more, that is, whether Δtn is Tn or more. If step S5 is negative, the process proceeds to step S6, where 1 is added to s as a short-circuit between the electrodes 11 to 15 occurs earlier than during normal wear, that is, an abnormality has occurred. On the other hand, if step S5 is affirmed, it is determined that the short circuit is caused by normal wear, and step S6 is passed and the process proceeds to step S7.

  In step S7, it is determined whether the number of occurrences s of the abnormality is 2 or less. If step S7 is negative, that is, if it is determined that s = 3, the process proceeds to step S8. In step S8, it is determined that the abnormality is apparent from the fact that the abnormality has been counted three times. For example, a control signal is output to the display device to indicate that the adsorption state of the metal particles is abnormal via the display device. Inform the user. On the other hand, if step S7 is affirmed, step S8 is passed and the process proceeds to step S9. In step S9, it is determined whether n is 3 or less. If step S9 is positive, the process proceeds to step S10, 1 is added to n, and the process returns to step S3. If step S9 is negative, the process ends. In addition, you may make it alert | report to a user via a display apparatus etc. that the process was complete | finished.

  The operation of this embodiment will be described more specifically. Immediately after starting the process of FIG. 5, n = 1. In this case, if there is no short circuit between the electrodes 11 and 12, the detected voltage value V and the calculated value (R1 + R2 + R3 + R4) · V0 / (R0 + R1 + R2 + R3 + R4) are equal. When the electrodes 11 and 12 are short-circuited after the time Δt1, the voltage detection value V becomes smaller than the calculated value. At this time, as shown in FIG. 4, if Δt1 is equal to or greater than T1, it is normal wear, 1 is not added to s (step S5 → step S7), 1 is added to n, and n = 2 ( Step S10).

  If n = 2 and there is no short circuit between the electrodes 12 and 13, the detected voltage value V and the calculated value (R2 + R3 + R4) · V0 / (R0 + R2 + R3 + R4) are equal. When the electrodes 12 and 13 are short-circuited after the time Δt2, the voltage detection value V becomes smaller than the calculated value. At this time, as shown in FIG. 4, if Δt2 is equal to or greater than T2, it indicates normal wear, 1 is not added to s, 1 is added to n, and n = 3.

  If there is no short circuit between the electrodes 13 and 14 at n = 3, the detected voltage value V and the calculated value (R3 + R4) · V0 / (R0 + R3 + R4) are equal. When the electrodes 13 and 14 are short-circuited after the time Δt3, the voltage detection value V becomes smaller than the calculated value. At this time, as shown in FIG. 4, if Δt3 is smaller than T3, it is abnormal, and 1 is added to s, so that s = 1 (step S6). Also, 1 is added to n, so that n = 4.

  When n = 4 and there is no short circuit between the electrodes 14 and 15, the detected voltage value V is equal to the calculated value (R4) · V0 / (R0 + R4). When the electrodes 14 and 15 are short-circuited after the time Δt4, the voltage detection value V becomes smaller than the calculated value. At this time, as shown in FIG. 4, if Δt4 is smaller than T4, it is abnormal, and 1 is added to s, so that s = 2 (step S6). Thus, the process in the determination device 30 ends. Since n = 4 at the end of the process, metal particles are adsorbed on almost the entire surface of the sensor unit 4 and it is necessary to replace or clean the sensor. This is because of the voltage V displayed on the display device. The user can grasp based on the change.

  On the other hand, in FIG. 4, if Δt2 is smaller than T2, s = 3. In this case, it is notified that the metal particles in the pipeline 1 have increased abnormally (step S8). This makes it possible to distinguish between the adsorption of metal particles due to normal wear of the hydraulic equipment and the adsorption of metal particles due to the occurrence of an abnormality, and the user can recognize early that an abnormality has occurred in the hydraulic equipment or the like.

According to the present embodiment, the following operational effects can be achieved.
(1) The voltage value V that changes due to a short circuit between the electrodes 11 to 15 is detected by the voltage detector 26, and the time Δt1 to Δt4 and the standard elapsed time T1 that are required for the detected voltage value V to change are detected. Based on the relationship with T4, it was determined whether or not the degree of increase in metal particles was abnormal. This makes it possible to accurately determine whether or not an abnormality has occurred in the hydraulic device, distinguishing it from normal wear.
(2) Counting the number of times that the time Δt1 to Δt4 required for the voltage change is shorter than the standard elapsed time T1 to T4, and if the count value s exceeds the predetermined number (twice), it is an obvious abnormality. And the user is notified of the abnormality via the display device. Thereby, even if Δti <Ti is detected, if the number of times is less than the predetermined number, the abnormality is not notified, so that it is possible to prevent erroneous notification of abnormality.
(3) Since the change in the detection voltage V is displayed on the display device, the user can recognize the degree of adsorption of the metal particles and can determine whether the sensor needs to be replaced or cleaned.
(4) While providing the center electrode 11 in the center part of the sensor body 2, the several ring-shaped electrodes 12-15 are provided concentrically centering on this center electrode 11, and distance w1 between each adjacent electrodes 11-15 is provided. Since w4 is made different from each other, the electrodes 11 to 15 are short-circuited in order, and the change in the adsorption amount of the metal particles can be easily grasped.

  In the above embodiment, the determination device 29 determines whether or not the degree of increase of the metal particles is abnormal based on the time change of the voltage detection value V. However, the voltage detection value V And the time may be stored in the recording device 28 as a storage means, and the user himself / herself may make an abnormality determination using the storage result, and the determination device is not necessarily required. Further, the signal from the voltage detector 26 may be directly input to the determination device 29 to determine the abnormality, and the recording device 28 is not necessarily required.

  In the above embodiment, the abnormality is determined based on the time Δt1 to Δt4 required for the voltage change due to the short circuit between the electrodes and the standard elapsed time T1 to T4 (reference time), and the time Δt1 to Δt4 required for the voltage change is determined. The number of times shorter than the standard elapsed time T1 to T4 is counted, and when the count value s exceeds the predetermined number of times, it is determined to be abnormal. However, the abnormality is determined based on the relationship between the voltage detection value V and time. If it is, the process in the determination apparatus 29 as a determination means is not restricted to what was mentioned above.

  In the above embodiment, the center electrode 11 and the plurality of ring electrodes 12 to 15 are provided in the sensor body 2, but the number of electrodes and the shape of the electrodes are not limited thereto. Although the permanent magnet 18 is used as the adsorption means for adsorbing the metal particles mixed in the oil to the electrodes 11 to 16, an electromagnet may be used. The configuration of the electric circuit is not limited to that illustrated in FIG. 2 as long as the electrodes are configured to be short-circuited by the adsorbed metal particles. Although the voltage detector 28 detects the voltage value V that changes due to a short circuit between the electrodes, the detection means is not limited to this.

  In the above embodiment, the sensor body 2 is attached to the oil pipe 1, but it may be attached to an oil tank or the like. That is, the present invention is not limited to the metal particle detection device of the embodiment as long as the features and functions of the present invention can be realized.

The figure which shows the attachment state of the metal particle detection apparatus which concerns on embodiment of this invention. The figure which shows the principal part structure of the metal particle detection apparatus which concerns on 1st Embodiment. FIG. 3 is an arrow III view of FIG. 1. The figure which shows an example of the detection voltage of the metal particle detection apparatus which concerns on this Embodiment. The flowchart which shows an example of the process in the determination apparatus of FIG.

Explanation of symbols

2 Sensor body 11 Center electrode 12-16 Ring electrode 17 Magnet 20-25 Resistor 26 Voltage detector 27 Power supply 28 Recording device 29 Judgment device

Claims (5)

A plurality of electrodes disposed in the sensor body so as to be spaced apart from each other and immersed in oil;
Adsorbing means for adsorbing metal particles mixed in oil to the electrode;
An electrical circuit configured such that the electrodes are short-circuited by the metal particles adsorbed by the adsorption means;
Detecting means for detecting a voltage value that changes due to a short circuit between the electrodes;
A metal particle detection apparatus comprising: storage means for storing a relationship between a voltage value detected by the detection means and time. A plurality of electrodes that are arranged apart from each other in the sensor body and are immersed in oil;
Adsorbing means for adsorbing metal particles mixed in oil to the electrode;
An electrical circuit configured such that the electrodes are short-circuited by the metal particles adsorbed by the adsorption means;
Detecting means for detecting a voltage value that changes due to a short circuit between the electrodes;
A metal particle detection apparatus comprising: determination means for determining whether or not the degree of increase in metal particles is abnormal based on the relationship between the voltage value detected by the detection means and time. The metal particle detector according to claim 2,
The determination means determines whether or not the degree of increase of the metal particles is abnormal based on a time required for the voltage to change due to a short circuit between the electrodes and a reference time predetermined corresponding thereto. A metal particle detector characterized by determining. In the metal particle detection apparatus according to claim 3,
The said determination means counts the frequency | count that the time required for the said change of the voltage became shorter than the said reference time, and determines that it is abnormal when the count value exceeds a predetermined frequency | count. In the metal particle detection apparatus according to claims 1 to 4,
The plurality of electrodes includes a center electrode provided at a central portion of the sensor body and a plurality of ring electrodes formed concentrically with the center electrode as a center, and the distance between adjacent electrodes is mutually A metal particle detection device characterized in that it is set to a different value.

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