JP2019035681A - Metallic foreign matter detector - Google Patents

Abstract

To provide a metallic foreign matter detector with which it is possible to increase accuracy of detecting metallic foreign matter even when the metallic foreign matter included in fluid is small.SOLUTION: A metallic foreign matter detector detects a metallic foreign matter included in fluid flowing in a pipeline. The metallic foreign matter detector comprises a non-metallic conduit formed of a non-metallic material and constituting at least a portion of the pipeline, and a detection unit for detecting the metallic foreign matter included in the fluid flowing in the non-metallic conduit, the detection unit including a plurality of coils arranged in the middle of the non-metallic conduit and lying in a row in a direction in which the fluid flows and a detection circuit for detecting, for each of the plurality of coils, a change of self-inductance when the metallic foreign matter passes through.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a metal foreign object detection device, and more particularly to a metal foreign object detection device that detects a metal foreign material contained in a fluid flowing through a pipeline.

  For example, in an apparatus using lubricating oil such as an internal combustion engine or a transmission, metal powder generated due to wear of components constituting the apparatus is included in the lubricating oil. If the lubricating oil contains metal powder, not only the lubricating performance of the lubricating oil but also the operation and life of the apparatus may be adversely affected.

  Therefore, it is conceivable to detect the metal powder contained in the lubricating oil and grasp the state of the apparatus. For example, in the following Non-Patent Document 1, it is proposed that the lubricating oil in the rotating machine is collected and used for maintenance of the rotating machine by measuring the concentration of iron powder contained in the collected lubricating oil. Yes. However, in Non-Patent Document 1, it is possible to grasp the state of the rotating machine at the time of collecting the lubricating oil, but it is difficult to grasp the state of the rotating machine at the present time.

  In order to cope with such a problem, in the following Patent Document 1 and Patent Document 2, it is proposed to detect metal powder contained in the lubricating oil flowing through the piping provided in the apparatus. In the following Patent Document 1 and Patent Document 2, it is determined whether or not the metal powder is contained in the lubricating oil flowing through the piping by detecting a change in the inductance of the coil when the metal powder passes. .

Japanese Patent No. 4189967 Japanese Patent No. 4014605

Diagnosis of rotating machinery with iron powder densitometer: Journal of Japan Marine Engineering Society, Vol.42, No.4, pp91-97

  The magnitude of the change in the self-inductance of the coil when the metal powder passes depends on the size of the metal powder when the coil size is the same. Therefore, when the metal powder is small, the change itself is small. As a result, it becomes difficult to distinguish the change from the noise, and it is difficult to determine whether the lubricating oil contains metal powder.

  An object of the present invention is to provide a metal foreign object detection device capable of improving the detection accuracy of a metal foreign object even when the metal foreign object contained in the fluid is small.

  In order to achieve the above object, the inventor of the present application has proceeded with investigation focusing on the number of times metal foreign objects are detected. And it came to the knowledge that the opportunity to detect a metal foreign material could be obtained several times if a plurality of coils were arranged in the direction in which fluid flows. The present invention has been completed based on such findings.

  A metal foreign object detection device according to the present invention is a metal foreign object detection device that detects a metal foreign object contained in a fluid flowing through a pipeline, and is formed of a non-metallic material and constitutes at least a part of the pipeline. A metal pipe and a detection unit for detecting the metal foreign matter contained in the fluid flowing through the non-metal pipe, and the detection unit is disposed in the middle of the non-metal pipe, A plurality of coils arranged in the flowing direction, and a detection circuit that detects a change in self-inductance when the metal foreign object passes through each of the plurality of coils.

  In the metal foreign object detection device, since the plurality of coils are arranged in the direction in which the fluid flows, an opportunity to detect the metal foreign object contained in the fluid multiple times is obtained. For this reason, the detection accuracy of the metallic foreign matter is improved.

  In the metal foreign object detection device, preferably, the detection unit further detects, when the detection circuit detects a change in the self-inductance when the metal foreign object passes, for at least one of the plurality of coils. A determination circuit configured to determine that the metal foreign matter is contained in the fluid flowing through the non-metallic pipe line;

  In the above aspect, the metallic foreign matter is detected when a change in self-inductance associated with the passage of the metallic foreign matter is detected even once. Therefore, there is a high possibility that even a small detection signal can be detected.

  In the metal foreign object detection device, preferably, the detection unit further detects a change in the self-inductance when the metal foreign object passes through two or more predetermined coils among the plurality of coils. The metal foreign matter is included in the fluid flowing through the non-metallic pipe line only when the detection circuit detects the change and the self-inductance change is based on the same metal foreign matter. And a determination circuit that determines that it is present.

  In the above aspect, when the change in the self-inductance accompanying the passage of the metal foreign object is detected twice or more and the detection is for the same metal foreign object, the metal foreign object is detected. Therefore, compared with the case where the metal foreign object is detected only by detecting the change of the self-inductance accompanying the passage of the metal foreign object once, the reliability with respect to the detection of the metal foreign object can be improved. This is because if the change in the self-inductance due to the passage of the metal foreign object is detected only once, the change in the self-inductance may be caused by noise. This is because it is difficult to consider that any change in self-inductance is caused by noise if the change in self-inductance caused by the passage of two or more is detected twice or more.

  In the metal foreign object detection device, preferably, the determination circuit detects a change in the self-inductance when the metal foreign object passes through more than half of the plurality of coils. Only when the change in self-inductance is based on the same metal foreign matter, it is determined that the metal foreign matter is contained in the fluid flowing through the non-metallic conduit.

  In the above aspect, when a change in self-inductance due to the passage of a metal foreign object is detected in more than half of the coils, and the detection is for the same metal foreign object, the metal foreign object is detected. Therefore, the reliability with respect to the detection of a metal foreign object can be further enhanced.

  In the metal foreign object detection device, it is preferable that the detection unit is further configured to detect the metal foreign object by the detection circuit when the determination circuit determines that the metal foreign object is contained in the fluid flowing through the non-metallic conduit. A calculation circuit for calculating a size of the metal foreign object based on the detected value indicating the change in the self-inductance;

  In said aspect, the magnitude | size of a metal foreign material can be grasped | ascertained.

  In the metal foreign object detection device, preferably, the detection unit further includes an information collection circuit that collects information on the size of the metal foreign object calculated by the calculation circuit.

  In the above aspect, for example, it is possible to grasp the change in the total amount of metal foreign objects, the size of metal foreign objects, and the like in the period from the start of collecting the sizes of metal foreign objects.

  In the metal foreign object detection device, preferably, the detection unit further includes a switching circuit that alternatively connects each of the plurality of coils to the detection circuit.

  In the above aspect, the detection circuit is shared by the plurality of coils. Therefore, it is not necessary to provide a detection circuit for each coil.

  Preferably, the metal foreign object detection device further includes a shield that covers the detection unit.

  In the above aspect, the signal indicating the change in the self-inductance of the coil when the metal foreign object passes through is hardly affected by noise.

  According to the metal foreign object detection device of the present invention, even when the metal foreign object contained in the fluid is small, the detection accuracy of the metal foreign object can be improved.

It is a schematic diagram which shows schematic structure of the metal foreign material detection apparatus by the 1st Embodiment of this invention. It is a block diagram which shows the signal processing circuit with which the metal foreign material detection apparatus shown in FIG. 1 is provided. It is a graph which shows the self-inductance of the coil detected by the detection circuit. It is a graph which shows the result of having calculated the rate of change of self-inductance. It is a graph which shows the change rate of the self-inductance corresponded to the detection signal extracted. It is a graph which shows that the self-inductance of each of three coils changed. It is a graph which shows that the self-inductance of each of three coils changed, Comprising: It is a graph which shows the state which match | combined the time axis with the 3rd coil. It is a graph for demonstrating the error time range of a detection signal. It is a graph which shows that the self-inductance of each of three coils changed. It is a graph which shows that the self inductance of each of the 1st coil and the 3rd coil changed among three coils. It is a graph which shows that the self-inductance of the 3rd coil changed among 3 coils. It is a signal detection process which a signal processing circuit performs, Comprising: It is a flowchart which shows the signal detection process about the self-inductance of the 1st coil. It is a signal detection process which a signal processing circuit performs, Comprising: It is a flowchart which shows the signal detection process about the self-inductance of the 2nd coil. It is a signal detection process which a signal processing circuit performs, Comprising: It is a flowchart which shows the signal detection process about the self-inductance of the 3rd coil. It is a flowchart which shows the determination process which a signal processing circuit performs in the 1st Embodiment of this invention. It is a flowchart which shows the determination process which a signal processing circuit performs in the application example of the 1st Embodiment of this invention. It is a schematic diagram which shows schematic structure of the metal foreign material detection apparatus by the 2nd Embodiment of this invention. It is a graph which shows that each self-inductance of two coils changed. It is a flowchart which shows the determination process which a signal processing circuit performs in the 2nd Embodiment of this invention. It is a flowchart which shows the determination process which a signal processing circuit performs in the application example of the 2nd Embodiment of this invention. It is a schematic diagram which shows schematic structure of the switching apparatus provided in the detection unit with which the metal foreign material detection apparatus by the 3rd Embodiment of this invention is provided. It is a schematic diagram which shows schematic structure of the shield with which the metallic foreign material detection apparatus by the 4th Embodiment of this invention is provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  With reference to FIG. 1, a metal foreign object detection apparatus 10 according to a first embodiment of the present invention will be described. FIG. 1 is a schematic diagram illustrating a schematic configuration of the metal foreign object detection device 10.

  The metal foreign object detection device 10 detects a metal foreign object contained in lubricating oil as a fluid flowing through a pipe 11 as a pipe line. Here, the piping 11 is provided in an internal combustion engine, for example, and flows lubricating oil. The metal foreign matter is, for example, metal powder generated by wear of parts constituting the internal combustion engine.

  In the following description, the flow passage cross section of a pipe is a cross section of a portion (cavity portion) through which the lubricating oil flows in the pipe, and a cross section in a direction perpendicular to the direction in which the lubricating oil flows.

  The metallic foreign object detection device 10 includes a non-metallic tube 12 as a non-metallic conduit and a detection unit 13. Hereinafter, these will be described.

  The non-metallic pipe 12 is formed of a non-metallic material and constitutes a part of the pipe 11. The non-metallic pipe 12 is, for example, an upstream pipe positioned upstream of the non-metallic pipe 12 in the direction in which the lubricating oil flows, and a downstream side of the non-metallic pipe 12 in the direction in which the lubricating oil flows. It arrange | positions between the downstream piping which connects, and connects these upstream piping and downstream piping. The channel cross section of the non-metallic pipe 12 is the same in size and shape as the channel cross sections of the upstream pipe and the downstream pipe. The flow path cross section of the non-metallic tube 12 is, for example, circular. The nonmetallic material forming the nonmetallic tube 12 may be, for example, a metal material or a synthetic resin material.

  The detection unit 13 includes a plurality (three in the present embodiment) of coils 141, 142, and 143, a plurality (three in the present embodiment) of detection circuits 161, 162, and 163, and a signal processing circuit 18. With.

  Each of the plurality of coils 141, 142, and 143 allows passage of metallic foreign matter contained in the lubricating oil flowing through the non-metallic pipe 12. Each of the plurality of coils 141, 142, and 143 changes in self-inductance as the metal foreign object passes.

  The plurality of coils 141, 142, and 143 are respectively disposed on the non-metallic tube 12. The plurality of coils 141, 142, 143 are arranged at equal intervals in the direction in which the lubricating oil flows.

  The plurality of coils 141, 142, and 143 are each formed by winding a coil winding around the central axis of the non-metallic tube 12. Each of the coils 141, 142, and 143 is a so-called solenoid coil. The plurality of coils 141, 142, and 143 have the same shape and size.

  In the example shown in FIG. 1, the plurality of coils 141, 142, and 143 are each formed by winding a coil winding around the outer peripheral surface of the non-metallic tube 12. Therefore, when the lubricating oil flows through the non-metallic pipe 12 in which the plurality of coils 141, 142, 143 are arranged, the metal foreign matter contained in the lubricating oil passes through the inside of each of the plurality of coils 141, 142, 143. It is supposed to be.

  The plurality of detection circuits 161, 162, and 163 detect changes in the self-inductance of the connected coil among the plurality of coils 141, 142, and 142, respectively. In the example shown in FIG. 1, the detection circuit 161 detects a change in the self-inductance of the coil 141, the detection circuit 162 detects a change in the self-inductance of the coil 142, and the detection coil 163 detects a change in the self-inductance of the coil 143. To do. The plurality of detection circuits 161, 162, and 163 may be formed on the same printed wiring board, for example, or may be formed on separate printed wiring boards.

  The plurality of detection circuits 161, 162, and 163 each detect a change in the self-inductance of the connected coil as follows. Here, since each of the plurality of detection circuits 161, 162, and 163 detects the self-inductance of the coil in the same manner, only the case where the detection circuit 161 detects the self-inductance of the coil 141 will be described below. explain.

  The detection circuit 161 measures the self-inductance of the coil 141 by, for example, measuring the resonance frequency of a resonance circuit including the coil 141 and a capacitor (not shown).

  Here, when a metal foreign object formed of a magnetic material passes through the coil 141, the self-inductance of the coil 141 measured as described above increases. On the other hand, when a metal foreign object formed of a non-magnetic material passes through the coil 141, the self-inductance of the coil 141 measured as described above decreases. The detection circuit 161 detects such a change in the self-inductance of the coil 141.

  The signal processing circuit 18 acquires information on the detected metal foreign object by using the self-inductance of the coil detected by each of the plurality of detection circuits 161, 162, and 163. The signal processing circuit 18 is connected to each of the plurality of detection circuits 161, 162, and 163. For example, the signal processing circuit 18 may be formed on the same printed wiring board as the plurality of detection circuits 161, 162, and 163. What is the printed wiring board on which the plurality of detection circuits 161, 162, and 163 are formed? It may be formed on another printed wiring board.

  The plurality of detection circuits 161, 162, 163 and the signal processing circuit 18 are realized, for example, when the central processing unit reads a program stored in the storage device and performs predetermined processing. Note that some of the plurality of detection circuits 161, 162, 163 and the signal processing circuit 18 may be realized by an integrated circuit such as an ASIC.

  The signal processing circuit 18 will be described with reference to FIG. FIG. 2 is a block diagram showing the signal processing circuit 18.

  The signal processing circuit 18 includes a signal extraction unit 181 as a signal extraction circuit, a determination unit 182 as a determination circuit, and an information collection unit 183 as an information collection circuit. Hereinafter, these will be described.

  The signal extraction unit 181 extracts a change in self-inductance corresponding to the passage of metal foreign matter from the coil self-inductance detected by each of the plurality of detection circuits 161, 162, and 163, that is, a detection signal indicating the passage of metal foreign matter. To do.

  The detection signal extraction by the signal extraction unit 181 will be described with reference to FIGS. Here, since the detection of the detection signal by the signal extraction unit 181 is the same regardless of the detection signal detected by any of the plurality of detection coils 161, 162, 163, in the following description, detection from the detection circuit 161 is performed. Only the case of extracting a signal will be described.

  FIG. 3 is a graph showing the self-inductance of the coil 141 detected by the detection circuit 161. FIG. 4 is a graph showing the result of calculating the rate of change of the self-inductance of the coil 141. FIG. 5 is a graph showing the rate of change of the self-inductance of the coil 141 corresponding to the extracted detection signal.

  First, the signal extraction unit 181 calculates a baseline. The baseline is used when determining the presence or absence of a detection signal. For example, as shown in FIG. 3, the baseline is an average value Ave of the self-inductance yt in the period immediately preceding the detection signal (in this embodiment, 1 second).

  Subsequently, the signal extraction unit 181 calculates a change rate Yt as a value indicating the detected change in the self-inductance yt by the following equation (1).

  According to the calculation result of the above formula (1), as shown in FIG. 4, the rate of change of the self-inductance is substantially zero in the portion corresponding to the baseline.

  Subsequently, the signal extraction unit 181 sets a threshold value TH (see FIG. 4) so that data near the baseline can be removed. The threshold value TH is set to a value larger than the baseline.

  Subsequently, as illustrated in FIG. 5, the signal extraction unit 181 sets data below the threshold value TH to zero. As a result, it is possible to extract a signal (detection signal) indicating a change in self-inductance due to the passage of the metal foreign object.

  Again, a description will be given with reference to FIG. The determination unit 182 confirms whether or not the plurality of detection signals extracted by the signal extraction unit 181 are due to the passage of the same metallic foreign object.

  Here, a method for confirming whether or not the detection signal extracted by the signal extraction unit 181 is caused by the passage of the same metal foreign object will be described with reference to FIGS. 6 and 7. FIG. 6 is a graph showing that the self-inductance of each of the plurality of coils 141, 142, 143 has changed. FIG. 7 is a graph showing that the self-inductance of each of the plurality of coils 141, 142, 143 has changed, and is a graph showing a state in which the time axis is aligned with the coil 143.

  When the metal foreign object sequentially passes through the plurality of coils 141, 142, and 143, the self-inductance of each of the plurality of coils 141, 142, and 143 changes as shown in FIG. Here, the time difference from when the metal foreign object passes through the coil 141 until it passes through the coil 143 is ΔT13, and the time difference from when the metal foreign object passes through the coil 142 to pass through the coil 143 is ΔT23.

  Note that ΔT13 and ΔT23 are determined by the flow rate of the lubricating oil. The flow rate of the lubricating oil is measured by a flow meter 20 provided in the pipe 11 or the nonmetallic pipe 12.

  Assume that the time axis of the self-inductance of the coil 141 is moved by ΔT13 and the time axis of the self-inductance of the coil 142 is moved by ΔT23. In such a case, as shown in FIG. 7, a change in self-inductance in coil 141 (detection signal) and a change in self-inductance in coil 142 (detection signal) respectively change in self-inductance in coil 143 (detection signal). ), It is confirmed that the change in the self-inductance (detection signal) in each of the plurality of coils 141, 142, 143 is caused by the same metal foreign matter.

  Here, there is a fluctuation in the speed at which the metallic foreign material flows (that is, the flow speed of the lubricating oil). Therefore, even when the most recent flow velocity is used, when the time axis of the self-inductance detected by the coil is moved as described above, the change in the self-inductance in each of the plurality of coils 141, 142, 143 ( Detection signal) may not exist at the same time.

  In consideration of such circumstances, a plurality of detection signals exist within a predetermined error time range Tx as shown in FIG. 8 in a state where the time axis of the self-inductance detected by the coil is moved as described above. By determining whether or not the change in the self-inductance (detection signal) in each of the plurality of coils 141, 142, and 143 is caused by the same metal foreign matter, it may be confirmed. . Note that the error time range Tx is, for example, about 1/10 of the time from when the metal foreign object passes through one of the two adjacent coils to the other.

  Again, a description will be given with reference to FIG. The determination unit 183 determines that the metal oil is contained in the lubricating oil when the plurality of detection signals extracted by the signal extraction unit 181 are caused by the passage of the same metal foreign material.

  Here, a method for determining whether or not a metallic foreign matter is contained in the lubricating oil will be described with reference to FIGS. 9, 10, and 11. FIG. 9 is a graph showing that the self-inductance of the plurality of coils 141, 142, 143 has changed. FIG. 10 is a graph showing that the self-inductance of each of the coil 141 and the coil 143 has changed. FIG. 11 is a graph showing that the self-inductance of the coil 143 has changed.

  The foreign metal contained in the lubricating oil sequentially passes through the plurality of coils 141, 142, and 143. Therefore, as shown in FIG. 9, a change (detection signal) of self-inductance that indicates the passage of metal foreign matter is detected in all of the plurality of coils 141, 142, and 143, and these detection signals are detected by the plurality of coils. If the detection is sequentially performed at predetermined intervals along the arrangement order of 141, 142, and 143, there is a very high possibility that the lubricant contains metallic foreign matter. However, for example, as shown in FIGS. 10 and 11, when no change (detection signal) of self-inductance indicating the passage of the metal foreign matter is detected in all of the plurality of coils 141, 142, and 143, the lubricating oil There is also a possibility that no metal foreign matter is contained in. Therefore, in the present embodiment, a change (detection signal) of self-inductance indicating the passage of a metal foreign object is detected in two or more coils among the plurality of coils 141, 142, 143, and these detections are made. If the signals are sequentially detected at predetermined intervals along the arrangement order of the plurality of coils 141, 142, 143, it is determined that the metal oil is contained in the lubricating oil. In addition, as a reference when it is determined that metal foreign matter is included in the lubricant, a change in self-inductance (detection signal) indicating the passage of the metal foreign matter in at least one of the plurality of coils 141, 142, and 143. Of course, it is possible to adopt the criterion that is detected.

  Again, a description will be given with reference to FIG. The information collecting unit 183 is determined by the determining unit 182 that the metal oil is contained in the lubricating oil because the plurality of detection signals extracted by the signal extracting unit 181 are caused by the passage of the same metal foreign material. In this case, based on a plurality of detection signals (change in self-inductance) that is the basis of the determination, information related to the size of the metal foreign matter that has passed is stored in a storage device (not shown). The information on the size of the metal foreign object may be calculated based on, for example, an average value of the rate of change of self-inductance, or calculated based on the maximum value of the rate of change of self-inductance. Good.

  A signal detection process executed by the signal processing circuit 18 will be described with reference to FIGS. 12, 13, and 14. FIG. 12 is a flowchart showing the signal detection process executed by the signal processing circuit 18 and the signal detection process for the self-inductance of the coil 141. FIG. 13 is a flowchart showing signal detection processing executed by the signal processing circuit 18 and regarding signal self-inductance of the coil 142. FIG. 14 is a flowchart showing signal detection processing executed by the signal processing circuit 18 and regarding signal self-inductance of the coil 143.

  Initially, with reference to FIG. 12, the signal detection process about the self-inductance of the coil 141 is demonstrated. In step S11, the signal processing circuit 18 acquires the self-inductance yt1x of the coil 141 at time t1x from the detection circuit 161.

  Subsequently, in step S12, the signal processing circuit 18 calculates the average value Ave1 of the self-inductance yt1x of the coil 141 for 1 second immediately before the time t1x when the self-inductance yt1x of the coil 141 is acquired from the detection circuit 161 in step S11. .

  Subsequently, in step S13, the signal processing circuit 18 calculates the rate of change Yt1 of the self-inductance yt1x of the coil 141 acquired from the detection circuit 161 in step S11.

  Subsequently, in step S14, the signal processing circuit 18 determines whether or not the rate of change Yt1 of the self-inductance yt1x of the coil 141 calculated in step S13 is larger than the threshold value TH.

  When the rate of change Yt1 of the self-inductance yt1x of the coil 141 calculated in step S13 is less than or equal to the threshold TH (step S14: NO), the signal processing circuit 18 determines the value of the rate of change Yt1 of the self-inductance yt1x of the coil 141 in step S15. And the time axis of the rate of change Yt1 of the self-inductance yt1x of the coil 141 is moved. Thereafter, the signal processing circuit 18 executes a determination process in step S16. Details of the determination process will be described later.

  Subsequently, in step S17, the signal processing circuit 18 determines whether or not an end command for ending the detection of the self-inductance yt1x of the coil 141 is input. When the end command has not been input (step S17: NO), the signal processing circuit 18 executes the processing after step S11. When the end command is input (step S17: YES), the signal processing circuit 18 ends the signal detection process. Note that the end command is output by a user operation, for example.

  When the change rate Yt1 of the self-inductance yt1x of the coil 141 calculated in step S13 is larger than the threshold value TH (step S14: YES), the signal processing circuit 18 determines the change rate Yt1 of the self-inductance yt1x of the coil 141 in step S18. After setting the value to the value of the rate of change Yt1 calculated in step S13, the processing after step S16 is executed.

  Next, a signal detection process for the self-inductance of the coil 142 will be described with reference to FIG. The signal detection process for the self-inductance of the coil 142 differs in the amount of movement on the time axis compared to the signal detection process for the self-inductance of the coil 141. Specifically, in the signal detection process for the self-inductance of the coil 141, the amount of movement on the time axis is ΔT13, whereas in the signal detection process for the self-inductance of the coil 142, the amount of movement on the time axis is ΔT23. It is. Other than this, since it is the same as the signal detection process for the self-inductance of the coil 141, a detailed description of the signal detection process for the self-inductance of the coil 142 is omitted.

  Next, with reference to FIG. 14, a signal detection process for the self-inductance of the coil 143 will be described. The signal detection process for the self-inductance of the coil 143 is different from the signal detection process for the self-inductance of the coil 141 in that the time axis is not moved. Other than this, since it is the same as the signal detection process for the self-inductance of the coil 141, a detailed description regarding the signal detection process for the self-inductance of the coil 143 is omitted.

  Next, the determination process executed by the signal processing circuit 18 will be described with reference to FIG. FIG. 15 is a flowchart showing the determination process executed by the signal processing circuit 18.

  First, in step S41, the signal processing circuit 18 determines whether or not a change (detection signal) in the self-inductance of the coil 141 due to the passage of the metal foreign object is detected. When a change (detection signal) in the self-inductance of the coil 141 due to the passage of the metallic foreign object is detected (step S41: YES), the signal processing circuit 18 in step S42 causes the coil 141 to pass through the passage of the metallic foreign object. It is determined whether or not there is a change (detection signal) in the self-inductance of the coil 142 due to the passage of the metallic foreign object within the error time range Tx with reference to the time when the self-inductance changes.

  When there is a change (detection signal) in the self-inductance of the coil 142 due to the passage of the metal foreign object (step S42: YES), the signal processing circuit 18 in step S43, the self-inductance of the coil 141 accompanying the passage of the metal foreign object. It is determined whether or not there is a change (detection signal) in the self-inductance of the coil 143 due to the passage of the metallic foreign object within the error time range Tx with the time at which is changed.

  When there is a change (detection signal) in the self-inductance of the coil 143 due to the passage of the metal foreign object (step S43: YES), the signal processing circuit 18 is detected by the plurality of coils 141, 142, 143 in step S44. The average value of the rate of change of self-inductance is calculated.

  Subsequently, in step S45, the signal processing circuit 18 calculates the size of the detected metal foreign object based on the average value of the change rate of the self-inductance calculated in step S44. Thereafter, in step S46, the signal processing circuit 18 stores the size of the metal foreign matter calculated in step S45 in a storage device (not shown), and ends the determination process.

  When there is no change (detection signal) in the self-inductance of the coil 143 due to the passage of the metallic foreign object (step S43: NO), the signal processing circuit 18 determines the self-inductance detected by the coil 141 and the coil 142 in step S47. After calculating the average value of the rate of change, the processing after step S45 is executed.

  If there is no change (detection signal) in the self-inductance of the coil 142 due to the passage of the metal foreign object (step S42: NO), the signal processing circuit 18 in step S48 causes the self-inductance of the coil 141 to accompany the passage of the metal foreign object. It is determined whether or not there is a change (detection signal) in the self-inductance of the coil 143 due to the passage of the metallic foreign object within the error time range Tx with the time at which is changed.

  When there is a change (detection signal) in the self-inductance of the coil 143 due to the passage of the metallic foreign object (step S48: YES), the signal processing circuit 18 determines the self-inductance detected by the coil 141 and the coil 143 in step S49. After calculating the average value of the rate of change, the processing after step S45 is executed.

  If there is no change (detection signal) in the self-inductance of the coil 143 due to the passage of the metal foreign object (step S48: NO), the signal processing circuit 18 determines in step S50 that the metal foreign object is not detected, and the determination. The process ends.

  When the change (detection signal) of the self-inductance of the coil 141 accompanying the passage of the metallic foreign object is not detected (step S41: NO), the signal processing circuit 18 in step S51, the self of the coil 142 accompanying the passage of the metallic foreign object. It is determined whether or not a change in inductance (detection signal) is detected.

  When the change (detection signal) of the self-inductance of the coil 142 due to the passage of the metal foreign object is detected (step S51: YES), the signal processing circuit 18 in step 52 determines the change in the coil 142 as the metal foreign object passes. It is determined whether or not there is a change (detection signal) in the self-inductance of the coil 143 due to the passage of the metallic foreign object within the error time range Tx with reference to the time when the self-inductance changes.

  When there is a change (detection signal) in the self-inductance of the coil 143 due to the passage of the metallic foreign object (step S52: YES), the signal processing circuit 18 determines the self-inductance detected by the coil 142 and the coil 143 in step S53. After calculating the average value of the rate of change, the processing after step S45 is executed.

  When there is no change (detection signal) in the self-inductance of the coil 143 due to the passage of the metal foreign object (step S52: NO), the signal processing circuit 18 determines in step S54 that the metal foreign object is not detected and the determination. The process ends.

  If there is no change (detection signal) in the self-inductance of the coil 142 due to the passage of the metal foreign object (step S51: NO), the signal processing circuit 18 determines in step S55 that the metal foreign object is not detected, and the determination. The process ends.

  In other words, in the present embodiment, as shown in Table 1, when the self-inductance is changed only in one coil, it is determined that the metal foreign object is not detected, and the self-inductance is detected in two or more coils. If it has changed, it is determined that a metal foreign object has been detected. Here, Table 1 shows the determination criteria when the signal processing circuit 18 performs the determination processing (determination criteria as to whether or not metallic foreign matter is included in the lubricating oil). In Table 1, a numerical value “1” indicates that there is a detection signal, and a numerical value “0” indicates that there is no detection signal.

  In such a metal foreign object detection device 10, since it is determined that a metal foreign object has been detected when the self-inductance changes in two or more coils, the reliability with respect to the detection of the metal foreign object is increased. For this reason, the detection accuracy of the metallic foreign matter is improved.

  Here, in the metal foreign object detection device 10, when the self inductance changes in two or more coils, it is confirmed whether or not these changes in self inductance are caused by the passage of the same metal foreign object. Further, the reliability with respect to detection of metallic foreign matter is further increased.

  Further, since the size of the metal foreign object is calculated based on the detected change rate of the self-inductance in the metal foreign object detection device 10, the size of the detected metal foreign object can be grasped.

  In addition, since the metal foreign object detection device 10 collects information on the size of the detected metal foreign object, the total amount of metal foreign objects and the size of the metal foreign object in the period from the start of the collection of the information to the present. It is possible to grasp how the height changes.

[Application example of the first embodiment]
Next, a determination process executed by the signal processing circuit 18 in the application example of the first embodiment will be described with reference to FIG. FIG. 16 is a flowchart illustrating a determination process executed by the signal processing circuit 18 in the application example of the first embodiment.

  In the determination process according to this application example, when the self-inductance of at least one of the coils 141, 142, 143 changes compared to the determination process according to the first embodiment, the metallic foreign object It is different in that it is determined that has been detected. Specifically, it is as follows.

  In the determination process according to this application example, step S50A is performed instead of step S50 in the determination process according to the first embodiment. In step S50A, the signal processing circuit 18 sets the rate of change Yt1 of the self-inductance yt1 of the coil 141 as the rate of change Yt used for calculating the size of the metal foreign object. Thereafter, the signal processing circuit 18 ends the determination process.

  In the determination process according to this application example, step S54A is performed instead of step S54 in the determination process according to the first embodiment. In step S54A, the signal processing circuit 18 sets the rate of change Yt2 of the self-inductance yt2 of the coil 142 as the rate of change Yt used for calculating the size of the metal foreign object. Thereafter, the signal processing circuit 18 ends the determination process.

  In the determination process according to this application example, step S55A is performed instead of step S55 in the determination process according to the first embodiment. In step S55A, the signal processing circuit 18 determines whether or not a change (detection signal) in the self-inductance of the coil 143 due to the passage of the metal foreign object is detected.

  When the change (detection signal) of the self-inductance of the coil 143 due to the passage of the metal foreign object is detected (step S55A: YES), the signal processing circuit 18 changes the rate Yt3 of the self-inductance yt3 of the coil 143 in step S56. Is used as the rate of change Yt used to calculate the size of the metal foreign object, and then the determination process ends.

  When the change (detection signal) of the self-inductance of the coil 143 due to the passage of the metal foreign object is not detected (step S55A: YES), the signal processing circuit 18 determines in step S57 that the metal foreign object is not detected. Thereafter, the determination process is terminated.

  That is, in this application example, as shown in Table 2, when the self-inductance changes in at least one coil, it is determined that a metal foreign object has been detected, and any of the plurality of coils 141, 142, 143 is self-existing. If the inductance has not changed, it is determined that no metallic foreign matter has been detected. Here, Table 2 shows determination criteria when the signal processing circuit 18 performs determination processing in this application example (determination criteria as to whether or not metallic foreign matter is included in the lubricating oil). In Table 2, the numerical value “1” indicates that there is a detection signal, and the numerical value “0” indicates that there is no detection signal.

  In this application example, it is determined that a metal foreign object has been detected when the self-inductance of at least one coil has changed, so that there is a high possibility that even a small detection signal can be detected. Therefore, in this application example, the detection accuracy of the metal foreign object can be improved.

[Second Embodiment]
With reference to FIG. 17, a metal foreign object detection device 10A according to a second embodiment of the present invention will be described. FIG. 17 is a schematic diagram illustrating a schematic configuration of the metal foreign object detection device 10A.

  The metal foreign object detection device 10 </ b> A is different from the metal foreign object detection device 10 in that the coil 143 is not provided.

  In metallic foreign object detection device 10A, as shown in FIG. 18, a change (detection signal) in self-inductance associated with the passage of metallic foreign objects is detected in a plurality (two in the present embodiment) of coils 141 and 142. (See B1 and B2 in FIG. 18), or when a change (detection signal) of self-inductance due to the passage of a metal foreign object is detected in only one of the plurality of coils 141 and 142 (see C1 and D2 in FIG. 18) )

  Here, a change (detection signal) of self-inductance due to the passage of the metal foreign matter is detected in the plurality of coils 141 and 142, and these detection signals are predetermined along the arrangement order of the plurality of coils 141 and 142. If it is sequentially detected at intervals, it is considered that there is almost no doubt that the lubricating oil contains metallic foreign matter, so it is easy to determine that the lubricating oil contains metallic foreign matter. However, if no change in the self-inductance (detection signal) indicating the passage of the metallic foreign matter is detected in all of the plurality of coils 141 and 142, it is difficult to determine whether or not the metallic foreign matter is included in the lubricating oil. By the way. Therefore, in the present embodiment, a change in the self-inductance (detection signal) indicating the passage of the metallic foreign matter is detected in all of the plurality of coils 141 and 142, and these detection signals are detected by the plurality of coils 141 and 142. If it is sequentially detected at a predetermined interval along the arrangement order, it is determined that the metal oil is contained in the lubricating oil. In addition, as a reference when determining that metal foreign matter is included in the lubricating oil, a change (detection signal) of self-inductance indicating the passage of the metal foreign matter is detected in at least one of the plurality of coils 141 and 142. Naturally, it is possible to adopt the standard of being made.

  A determination process executed by the signal processing circuit 18 in the present embodiment will be described with reference to FIG. FIG. 19 is a flowchart showing the determination process executed by the signal processing circuit 18 in the present embodiment. Note that the signal detection process executed by the signal processing circuit 18 in the present embodiment is the same as the signal detection process (see FIGS. 12, 13, and 14) executed by the signal processing circuit 18 in the first embodiment. Therefore, detailed description thereof is omitted.

  First, in step S81, the signal processing circuit 18 determines whether or not a change (detection signal) in the self-inductance of the coil 141 due to the passage of the metal foreign object is detected.

  When a change (detection signal) in the self-inductance of the coil 141 due to the passage of the metal foreign object is detected (step S81: YES), the signal processing circuit 18 sets the time when the self-inductance of the coil 141 changes in step S82. It is determined whether or not a change (detection signal) of the self-inductance of the coil 142 due to the passage of the metallic foreign object exists within the reference error time range Tx.

  When the change (detection signal) of the self-inductance of the coil 142 due to the passage of the metallic foreign object is detected (step S82: YES), the signal processing circuit 18 is detected by the plurality of coils 141 and 142 in step S83. The average value of the rate of change of self-inductance is calculated.

  Subsequently, in step S84, the signal processing circuit 18 calculates the size of the detected metal foreign object based on the average value of the change rate of the self-inductance calculated in step S83. Thereafter, in step S85, the signal processing circuit 18 stores the size of the metal foreign object calculated in step S84, and ends the determination process.

  When the change (detection signal) of the self-inductance of the coil 142 due to the passage of the metal foreign object is not detected (step S82: NO), the signal processing circuit 18 determines that the metal foreign object is not detected in step S86. The determination process is terminated.

  When the change (detection signal) of the self-inductance of the coil 141 due to the passage of the metal foreign object is not detected (step S81: NO), the signal processing circuit 18 determines that the metal foreign object is not detected in step S87. The determination process is terminated.

  That is, in this embodiment, as shown in Table 3, it is determined that a metal foreign object has been detected only when the self-inductance has changed in all of the plurality of coils 141 and 142. Here, Table 3 shows the determination criteria when the signal processing circuit 18 performs the determination processing in the second embodiment (determination criteria as to whether or not metallic foreign matter is included in the lubricating oil). In Table 3, the numerical value “1” indicates that there is a detection signal, and the numerical value “0” indicates that there is no detection signal.

  In such a metal foreign object detection device 10A, since it is determined that a metal foreign object has been detected when the self-inductance has changed in all of the plurality of coils 141 and 142, the reliability of the metal foreign object detection itself can be improved. . Therefore, it is possible to improve the detection accuracy of the metallic foreign object.

[Application example of second embodiment]
Next, determination processing executed by the signal processing circuit 18 in the application example of the second embodiment will be described with reference to FIG. FIG. 20 is a flowchart illustrating a determination process executed by the signal processing circuit 18 in the application example of the second embodiment.

  The determination process according to this application example detects a metallic foreign object when the self-inductance of at least one of the plurality of coils 141 and 142 changes compared to the determination process according to the second embodiment. It is different in that it is determined that it has been done. Specifically, it is as follows.

  In the determination process according to this application example, step S86A is performed instead of step S86 in the determination process according to the second embodiment. In step S86A, the signal processing circuit 18 sets the rate of change Yt1 of the self-inductance yt1 of the coil 141 as the rate of change Yt used for calculating the size of the metal foreign object. Thereafter, the signal processing circuit 18 ends the determination process.

  In the determination process according to this application example, step S87A is performed instead of step S87 in the determination process according to the second embodiment. In step S87A, the signal processing circuit 18 determines whether or not a change (detection signal) in the self-inductance of the coil 142 due to the passage of the metal foreign object is detected.

  When the change (detection signal) of the self-inductance of the coil 142 due to the passage of the metal foreign object is detected (step S87A: YES), the signal processing circuit 18 changes the amount of change Yt2 of the self-inductance yt2 of the coil 142 in step S88. Is set to the change rate Yt used for calculating the size of the metal foreign object, and then the determination process is terminated.

  When the change (detection signal) of the self-inductance of the coil 142 due to the passage of the metal foreign object is not detected (step S87A: YES), the signal processing circuit 18 determines in step S89 that the metal foreign object is not detected. Thereafter, the determination process is terminated.

  That is, in this application example, as shown in Table 4, when the self-inductance changes in at least one coil, it is determined that a metal foreign object has been detected, and any of the plurality of coils 141, 142, 143 is self-examined. If the inductance has not changed, it is determined that no metallic foreign matter has been detected. Here, Table 4 shows the determination criteria when the signal processing circuit 18 performs the determination processing in this application example (determination criteria as to whether or not metallic foreign matter is included in the lubricating oil). In Table 4, a numerical value “1” indicates that there is a detection signal, and a numerical value “0” indicates that there is no detection signal.

  In this application example, when the self-inductance is changed in at least one of the plurality of coils 141 and 142, it is determined that the metal foreign object has been detected. Therefore, there is a high possibility that even a small detection signal can be detected. Become. Therefore, in this application example, the detection accuracy of the metal foreign object can be improved.

[Third Embodiment]
With reference to FIG. 21, a metal foreign object detection device according to a third embodiment of the present invention will be described. FIG. 21 is a schematic diagram illustrating a schematic configuration of a detection unit 13B included in the metal foreign object detection device according to the third embodiment.

  The metal foreign object detection device according to the present embodiment is different from the metal foreign object detection device 10 in that a detection unit 13B is provided instead of the detection unit 13. The detection unit 13B is different from the detection unit 13 in that it includes one detection circuit 16 and one switching circuit 22 instead of including a plurality of detection circuits 161, 162, and 163.

  The switching circuit 22 connects any one of the plurality of coils 141, 142, and 143 to the detection circuit 16. The switching circuit 22 includes two switch circuits 221 and 222. The switching circuit 22 selectively connects the coils 141, 142, and 143 to the detection circuit 16 by operating each of the two switch circuits 221 and 222 at an appropriate timing.

  Even in such a metal foreign object detection device, the same effect as that of the first embodiment can be obtained.

  In the above embodiment, since the switching circuit 22 is provided, one detection circuit 16 is shared by the plurality of coils 141, 142, and 143. As a result, it is not necessary to provide one detection circuit 16 for each of the plurality of coils 141, 142, and 143.

[Fourth Embodiment]
With reference to FIG. 22, a metal foreign object detection device 10D according to a fourth embodiment of the present invention will be described. FIG. 22 is a schematic diagram showing a schematic configuration of the shield 24 provided in the metal foreign object detection device 10D.

  The metal foreign object detection device 10 </ b> D differs from the metal foreign object detection device 10 in that it includes a shield 24. The shield 24 covers the detection unit 13.

  In such a metal foreign object detection device 10D, the same effect as that of the metal foreign object detection device 10 can be obtained.

  In the metal foreign object detection device 10 </ b> D, the shield 24 covers the detection unit 13. Therefore, when the detection circuits 161, 162, and 163 detect changes in the self-inductance of the coils 141, 142, and 143, they are less susceptible to noise.

  As mentioned above, although embodiment of this invention was explained in full detail, these are illustrations to the last, Comprising: This invention is not interpreted restrictively at all by description of the above-mentioned embodiment.

  The pipe line of the present invention may be formed of only a non-metallic pipe line.

  The non-metallic pipe line of the present invention may be disposed inside the pipe line. That is, the aspect in which the non-metallic pipe line constitutes at least a part of the pipe line includes an aspect in which the non-metallic pipe line is disposed inside the pipe line. In this case, the non-metallic pipe line is realized by, for example, a hole extending along the pipe line. For example, the coil may be disposed in a state of being inserted into the hole, or may be disposed in a state of being embedded around the hole.

  The coil of this invention may be arrange | positioned inside the nonmetallic conduit, and may be arrange | positioned in the state embedded at the nonmetallic conduit.

DESCRIPTION OF SYMBOLS 10 Metal foreign material detection apparatus 11 Piping path 12 Non-metallic pipe line 13 Detection unit 141 Coil 142 Coil 143 Coil 161 Detection circuit 162 Detection circuit 163 Detection circuit 182 Determination circuit 183 Information collection circuit 22 Switching circuit 24 Shield

Claims (8)

A metallic foreign matter detection device for detecting metallic foreign matter contained in a fluid flowing through a pipeline,
A non-metallic pipe formed of a non-metallic material and constituting at least a part of the pipe;
A detection unit for detecting the metallic foreign matter contained in the fluid flowing through the non-metallic pipe line,
The detection unit is
A plurality of coils arranged in the middle of the non-metallic conduit and arranged in a direction in which the fluid flows;
A metal foreign object detection device including a detection circuit that detects a change in self-inductance when the metal foreign object passes through each of the plurality of coils. The metal foreign object detection device according to claim 1,
The detection unit further comprises:
When the detection circuit detects a change in the self-inductance when the metal foreign object passes through at least one of the plurality of coils, the metal foreign object is included in the fluid flowing through the non-metallic pipe line. A metal foreign object detection device including a determination circuit that determines that the object is present. The metal foreign object detection device according to claim 1,
The detection unit further comprises:
Of the plurality of coils, when the detection circuit detects a change in the self-inductance when the metal foreign object passes through a predetermined number of coils, and the self-inductance And a determination circuit that determines that the metal foreign matter is contained in the fluid flowing through the non-metallic pipe line only when the change in is based on the same metal foreign matter. The metal foreign object detection device according to claim 3,
The determination circuit is a case where the detection circuit detects a change in the self-inductance when the metal foreign matter has passed through more than half of the plurality of coils. The metal foreign object detection device that determines that the metal foreign object is contained in the fluid flowing through the non-metallic pipe line only when the change in inductance is based on the same metal foreign object. The metal foreign matter detection device according to any one of claims 2 to 4,
The detection unit further comprises:
Based on a value indicating a change in the self-inductance detected by the detection circuit when the determination circuit determines that the metal foreign matter is included in the fluid flowing through the non-metallic pipe line, A metal foreign object detection device including a calculation circuit for calculating the size of a foreign object. The metal foreign object detection device according to claim 5,
The detection unit further comprises:
A metal foreign object detection device including an information collection circuit that collects information on the size of the metal foreign object calculated by the calculation circuit. The metal foreign object detection device according to any one of claims 1 to 6,
The detection unit further comprises:
A metal foreign object detection device comprising a switching circuit that selectively connects each of the plurality of coils to the detection circuit. The metal foreign object detection device according to any one of claims 1 to 7, further comprising:
A metal foreign object detection device comprising a shield that covers the detection unit.

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