Conductive particle detection device and mechanical operation device

Abstract

To provide a conductive particle detecting device and a mechanical operation device capable of securely detecting conductive particles to be detected while suppressing an increase in size and reduction in degree of freedom in design.SOLUTION: A conductive particle detecting device includes a plurality of electrodes 51a and 51b, a permanent magnet 3, and a detection circuit 50. The plurality of electrodes 51a and 51b are arranged at intervals in a lubricant 13. The permanent magnet 3 accumulates conductive particles in the lubricant 13 between adjacent electrodes 51a and 51b by a magnetic force. The detection circuit 50 detects conductive particles to be detected on the basis of electrical resistance between the adjacent electrodes 51a and 51b. An attractive force of the permanent magnet 3 acting on the conductive particles between the adjacent electrodes 51a and 51b is set such that the lubricant 13 remains as a non-conductive layer around fine-sized conductive particles having a smaller particle size than the conductive particles to be detected.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a conductive particle detector and a mechanical operating device equipped with a conductive particle detector. [Background technology]

[0002] In mechanical operating devices that incorporate a mechanical operating mechanism such as a reducer, the inside of the casing is filled with a lubricating liquid to reduce wear of the operating mechanism. In this type of mechanical operating device, wear and damage occur to the mechanical parts as they are used over time, and the metal powder generated therein mixes with the lubricating liquid. If a large amount of metal powder gets mixed into the lubricating liquid, the lubricating liquid's function of suppressing wear of the operating mechanism decreases. In addition, the mixing of a large amount of metal powder into the lubricating liquid means that wear and damage have occurred in the operating mechanism.

[0003] For this reason, in this type of mechanical operating device, it is desirable to be able to detect from the outside when the amount of metal powder mixed in the lubricating liquid exceeds a specified amount. As a countermeasure, a device has been proposed in which the metal powder in the lubricating liquid is attracted by a permanent magnet, and the amount of attracted metal powder can be detected electrically (see, for example, Patent Document 1).

[0004] The metal powder detection device (conductive particle detection device) used in this mechanical operating device works by placing opposing electrodes across a gap on the outer surface of a cylindrical permanent magnet placed in the lubricating liquid, and detecting the resistance between the electrodes on either side of the gap to determine the amount of metal powder present in the lubricating liquid. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-331324 A Summary of the Invention [Problem to be solved by the invention]

[0006] In general, in a mechanical operating device, a large amount of fine initial wear powder (metal powder) is generated when the machine is operated for the first time, etc. For this reason, when a mechanical operating device is used for a long period of time, not only broken pieces and metal powder due to wear over time (hereinafter referred to as "detection target metal powder") that are originally to be detected are mixed into the lubricating fluid, but also initial wear powder that has almost no adverse effect on the operation of the operating mechanism.

[0007] For this reason, in the above-mentioned conductive particle detector, initial wear particles first gather between the electrodes with a gap therebetween, and the target metal particles adhere to the outside of the initial wear particles. For this reason, in order to reliably detect the target metal particles that are the object of detection, it is necessary to ensure a sufficiently large gap between the electrodes and a sufficiently large space for collecting the metal particles. However, if an attempt is made to ensure a sufficiently large gap between the electrodes and a sufficiently large space for collecting the metal particles, the conductive particle detector will become larger and the design freedom will be reduced.

[0008] The present invention provides a conductive particle detection device and a machine operating device that can reliably detect conductive particles as detection targets while preventing an increase in size and a decrease in design freedom. [Means for solving the problem]

[0009] A conductive particle detection device according to one aspect of the present invention comprises a plurality of electrodes spaced apart in a lubricating liquid, a permanent magnet that uses magnetic force to collect conductive particles in the lubricating liquid between adjacent electrodes, and a detection circuit that detects conductive particles to be detected based on the electrical resistance between the adjacent electrodes, and the adsorption force of the permanent magnet acting on the conductive particles between the adjacent electrodes causes the lubricating liquid to remain as a non-conductive layer around minute conductive particles that are smaller in diameter than the conductive particles to be detected. The conductive particles to be detected are brought into direct contact with each other by pushing aside the non-conductive layer of the lubricating liquid around the conductive particles. It is set as follows.

[0010] The conductive particles to be detected have a particle size of 10 μm or more, and the minute particle size has a particle size of less than 10 μm.

[0011] The fine particle size is preferably less than 2 μm.

[0012] The electrode may have a conductive protrusion that partially protrudes from a main surface on which the minute conductive particles are attached and accumulated.

[0013] The protrusion is preferably made of a conductive non-magnetic material.

[0014] It is desirable that the magnetic force of the permanent magnet is set so that the minute conductive particles that adhere to and accumulate on the electrode become saturated and disperse to the surroundings without completely covering the protrusions.

[0015] The magnetic force of the permanent magnet may be set so that, in the one of the multiple types of mechanical operating devices to which it is applied that generates the largest amount of conductive particles, the fine conductive particles that adhere to and accumulate on the electrode become saturated to the extent that they do not completely cover the protrusion and are dispersed into the surrounding area.

[0016] The protrusion may be formed by a protruding member separate from a main body of the electrode, and the protruding member may be pressed against the main body by a detection unit cover that covers the periphery of the main body of the electrode.

[0019] A mechanical operating device according to one aspect of the present invention comprises a mechanical operating mechanism, a casing that contains lubricating liquid together with the operating mechanism, and a conductive particle detection device that detects conductive particles mixed in the lubricating liquid. The conductive particle detection device comprises a plurality of electrodes spaced apart in the lubricating liquid, a permanent magnet that uses magnetic force to collect conductive particles in the lubricating liquid between adjacent electrodes, and a detection circuit that detects conductive particles to be detected based on the electrical resistance between the adjacent electrodes. The adhesive force of the permanent magnet acting on the conductive particles between the adjacent electrodes is effective to attract conductive particles having a diameter smaller than that of the conductive particles to be detected. The lubricating liquid remains as a non-conductive layer around the conductive particles, and the conductive particles to be detected directly contact each other by pushing aside the non-conductive layer of the lubricating liquid around the conductive particles. It is set as follows. Effect of the Invention

[0020] In the case of the conductive particle detection device described above, the lubricating liquid remains as a non-conductive layer around the conductive particles having a small particle size, which is smaller than the conductive particles to be detected, between the adjacent electrodes. Therefore, even if the initial wear particles, which are the conductive particles having a small particle size, gather between the adjacent electrodes, the function of the non-conductive layer around the initial wear particles can prevent the detection circuit from making a false detection. Therefore, when the conductive particle detection device described above is adopted, the gap between the electrodes and the collection space of the conductive particles can be suppressed from expanding, so that the conductive particles to be detected can be reliably detected while suppressing the size of the device and the reduction in the degree of freedom in design. [Brief description of the drawings]

[0021] [Figure 1] 1 is a partial cross-sectional side view of a reducer (mechanical operating device) according to an embodiment. [Diagram 2] 1 is a partially sectional perspective view of a conductive particle detection device according to a first embodiment. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2 . [Figure 4] FIG. 2 is a schematic cross-sectional view showing the function of the conductive particle detection device according to the first embodiment. [Diagram 5] Graph showing the relationship between the particle size of iron powder and the adsorptive force of a permanent magnet. [Figure 6] FIG. 6 is a schematic cross-sectional view of a conductive particle detection device according to a second embodiment. [Figure 7] FIG. 11 is a perspective view of a conductive particle detection device according to a third embodiment. [Figure 8] 8 is a partial cross-sectional perspective view of the conductive particle detection device shown in FIG. 7 taken along line VIII-VIII in FIG. 7. [Figure 9] FIG. 13 is a perspective view of a conductive particle detection device according to a fourth embodiment. [Figure 10] 10 is a partial cross-sectional perspective view of the conductive particle detector shown in FIG. 9 taken along line XX in FIG. [Figure 11] 10 is a cross-sectional view of the conductive particle detector shown in FIG. 9 taken along line XI-XI in FIG. 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Next, an embodiment of the present invention will be described with reference to the drawings. In the embodiments described below, the same reference numerals are used to designate common parts, and some overlapping descriptions will be omitted.

[0023] FIG. 1 is a partial cross-sectional side view of a speed reducer 10, which is one form of a mechanical operating device. The reducer 10 includes a reduction mechanism 11 that reduces the input rotation to a predetermined reduction ratio, and a casing 12 that houses the reduction mechanism 11. The inside of the casing 12 is filled with lubricating liquid 13 for lubricating the reduction mechanism 11 and other mechanical contact parts. In addition, a conductive particle detector 14 is attached to a wall 12a of the casing 12. The conductive particle detector 14 detects conductive particles such as metal powder that are mixed into the lubricating liquid 13. In this embodiment, the reduction mechanism 11 and other mechanical contact parts constitute a mechanical operating mechanism that is disposed inside a casing 12. In addition, the lubricating liquid filled in the casing 12 is non-conductive.

[0024] <Configuration of the First Embodiment> Fig. 2 is a perspective view showing a longitudinal cross section of a part of the conductive particle detection device 14. Fig. 3 is a cross section taken along line III-III in Fig. 2. The conductive particle detection device 14 includes a substantially cylindrical device body 16, a support block 17 fixed inside the device body 16, and a flexible printed wiring board 102 (wiring) supported by the support block 17. The conductive particle detection device 14 further includes four permanent magnets 3 connected to one end side of the flexible printed wiring board 102 in the longitudinal direction via relay pieces 4, and a detection board 18 connected to the other end side of the flexible printed wiring board 102 in the longitudinal direction.

[0025] The device body 16 is attached to the casing 12 (see FIG. 1) of the reducer 10 by penetrating the wall 12a of the casing 12. The device body 16 is formed of, for example, metal. The device body 16 has a cylindrical fixed tube 16a that is fastened and fixed into a screw hole that penetrates the wall 12a of the casing 12, and a flange portion 16b that is integrally formed with an end of the fixed tube 16a (the end on the side disposed on the outside of the casing 12).

[0026] A male screw 19 is formed on the outer peripheral surface of the fixed cylinder 16a to be screwed into a screw hole on the reducer 10 side. A cylindrical device cover 20 with a bottom is fixed to the outer end face of the flange portion 16b (the end face facing the outside of the casing 12) with a bolt 21 as a fastening member. The space between the device cover 20 and the flange portion 16b is sealed by a disk-shaped grommet 5 as a sealing member. The grommet 5 is formed integrally with a part of the insulating layer of the flexible printed wiring board 102. The flexible printed wiring board 102 is integrated with the grommet 5 so as to penetrate the grommet 5 in the thickness direction.

[0027] A detection board 18 is attached to the outer end face of grommet 5 (the end face facing the outside of casing 12). The outside of detection board 18 is covered by device cover 20. In addition, the outer peripheral edge of grommet 5 is sandwiched between device cover 20 and flange portion 16b and fixed to both. Grommet 5 seals between lubricant filled space 22 (see FIG. 1) inside casing 12 of reducer 10 and detection space 23 (the space inside device cover 20) in which detection board 18 is disposed.

[0028] The support block 17 is formed in a rectangular prism shape from a resin material. One end side in the longitudinal direction of the support block 17 (hereinafter referred to as the "base side") is fixed to the inside of the device body 16. The support block 17 is disposed along the axial direction of the fixed cylinder 16a. The other end side in the longitudinal direction of the support block 17 (hereinafter referred to as the "tip side") protrudes outward beyond the fixed cylinder 16a of the device body 16.

[0029] The outer peripheral surface and end surface of the tip side of the support block 17 are covered by a bottomed cylindrical detector cover 24. The detector cover 24 is integrally formed from a resin material. The detector cover 24 includes a peripheral wall 24a having four detection windows 25, and an end wall 24b that closes the axial end of the peripheral wall 24a. The four detection windows 25 of the peripheral wall 24a are disposed at equal intervals at positions spaced apart by approximately 90° on the outer periphery of the peripheral wall 24a. Each detection window 25 is formed in a substantially rectangular shape when viewed from the front. In addition, tapered surfaces 25a are provided on both edge portions of each detection window 25 along the circumferential direction of the peripheral wall 24a so that the opening area gradually increases toward the radially outward direction.

[0030] The end wall 24b of the detection unit cover 24 is riveted to the end face on the tip side of the support block 17. Reference numeral 26 in the drawing denotes a rivet for fixing the detection unit cover 24 to the support block 17.

[0031] As shown in FIG. 2, the flexible printed wiring board 102 has a base 102b in which one end of a conductive part is connected to the detection board 18, and branch parts 102c that branch in four directions from the base 102b and have ends of the conductive parts branched in the four directions connected to the corresponding relay pieces 4. The base 102b of the flexible printed wiring board 102 penetrates the grommet 5 in the thickness direction. The four branch parts 102c branched from the base 102b are arranged along the four faces on the outer periphery of the support block 17. Support grooves 27 (see FIG. 3) are formed on the four faces on the outer periphery of the support block 17 so as to run along the longitudinal direction of the support block 17. Each branch part 102c is supported by the support groove 27 on each face of the support block 17.

[0032] A roughly rectangular relay piece 4 made of a metallic magnetic material is connected to the terminal portion (conductive portion) at the tip side of each branch portion 102c by conductive adhesive, soldering, or the like. Each relay piece 4 is supported in each support groove 27 together with the branch portion 102c at the tip side of the support block 17. A corresponding permanent magnet 3 is attracted and fixed by magnetic force to a flat surface of each relay piece 4 facing the outer periphery of the support block 17. Each permanent magnet 3 is conductive and connected to a power source (not shown) through the conductive portion of the flexible printed wiring board 102 and the detection board 18. In this embodiment, a plurality of adjacent permanent magnets 3 on the outer periphery of the support block 17 are connected to a power source to form electrodes for resistance detection. However, the electrodes may be provided separately from the permanent magnets 3.

[0033] After the relay pieces 4 and the permanent magnets 3 are attached to each surface of the tip side of the support block 17 as described above, the detection unit cover 24 is then attached to the tip side of the support block 17. The detection unit cover 24 is aligned so that the four corresponding permanent magnets 3 are positioned inside the four detection windows 25 (inside the radial direction of the peripheral wall 24a). In this state, the detection unit cover 24 is riveted to the end surface of the support block 17. At this time, the end surface of the peripheral wall 24a of the detection unit cover 24 (the end surface opposite the end wall 24b) is abutted against the end surface of the fixed cylinder 16a of the device body 16.

[0034] The conductive particle detector 14 assembled as described above has its tip end (the permanent magnet 3 side) inserted into a screw hole in the wall 12a of the casing 12 of the reducer 10, and in this state, the fixed cylinder 16a of the device body 16 is screwed into the screw hole and fixed. When the casing 12 of the reducer 10 is filled with lubricating liquid 13 in this state, the multiple permanent magnets 3 and the detector cover 24 are submerged in the lubricating liquid 13.

[0035] The detection board 18 includes a detection circuit. The detection circuit of the detection board 18 detects the electrical resistance between the adjacent permanent magnets 3 on the outer periphery of the support block 17. The permanent magnets 3 on the outer periphery of the support block 17 are spaced apart from one another as shown in FIG. 3. Therefore, in the initial state in which the reduction gear 10 is submerged in the lubricating liquid 13, the resistance between the adjacent permanent magnets 3 is infinite. When the amount of metal powder (conductive particles) mixed into the lubricating liquid 13 increases with the use of the reduction gear 10 from this state, the metal powder mixed into the lubricating liquid 13 is attracted by the permanent magnets 3 of the conductive particle detection device 14. The attracted metal powder is attracted to the surface of each permanent magnet 3 through the detection window 25 of the detection unit cover 24, and is also attracted to the outer periphery of the detection unit cover 24 by the magnetic force of the permanent magnets 3.

[0036] As the amount of metal powder mixed in the lubricating liquid 13 increases, the amount of metal powder adsorbed to the outer circumferential surface of the detector cover 24 also increases. When the amount of metal powder adsorbed to the outer circumferential surface of the detector cover 24 exceeds a certain amount, the resistance value between adjacent permanent magnets 3 falls below a specified value, and this is detected by the detection board 18. If the detection board 18 is connected to a display device or warning device via a controller, it can notify an operator or the like that the amount of metal powder in the reducer 10 has increased above a specified amount.

[0037] Here, the adhesive force of the permanent magnet 3 acting on the metal powder is determined by the magnetic force of the permanent magnet 3 and the distance between adjacent permanent magnets 3 on the detection unit cover 24. The adhesive force of the permanent magnet 3 acting on the metal powder is also affected by factors such as the viscosity of the lubricating liquid 13. In the conductive particle detection device 14 of this embodiment, the adhesive force on the metal powder is set by adjusting each of the above factors so as to satisfy the following condition (a). Condition (a): The lubricating liquid 13 remains as a non-conductive layer around metal powder (conductive particles) having a fine particle size smaller than that of the metal powder (conductive particles) to be detected. The "metal powder to be detected" in condition (a) refers to wear powder and broken pieces of mechanical parts that occur during normal use, with a particle size of 10 μm or more, preferably 20 μm or more. Also, the "metal powder of minute particle size" in condition (a) refers to initial wear powder that occurs when the reducer 10 is used for the first time, with a particle size of less than 10 μm, preferably less than 2 μm.

[0038] Fig. 4 is a schematic cross-sectional view of the conductive particle detector 14, showing the function of the detector 14. Fig. 4(A) shows the conductive particle detector 14 adsorbing minute metal powder Ms (initial wear powder), and Fig. 4(B) shows the conductive particle detector 14 adsorbing detection target metal powder Ml (wear powder other than initial wear powder (including broken pieces)). 4 indicates a detection circuit for detecting the electrical resistance between two adjacent electrodes 51a, 51b (permanent magnets 3). Also, reference numeral 52 indicates a power source, and reference numeral 53 indicates a resistance detection section in the detection circuit 50. "OFF" indicated on the resistance detection section 53 in FIG. 4(A) indicates a state in which the detected resistance is greater than a predetermined value and the metal powder Ml to be detected is not detected, and "ON" indicated on the resistance detection section 53 in FIG. 4(B) indicates a state in which the detected resistance is equal to or less than the predetermined value and the metal powder Ml to be detected is detected.

[0039] In the conductive particle detection device 14 of this embodiment, the attraction force of the permanent magnet 3 to the metal powder is set so as to satisfy the above condition (a), so that the lubricating liquid 13 remains as a non-conductive layer around the minute metal powder Ms as shown in Fig. 4(A). Therefore, even if the minute metal powder Ms is attracted and piled up between the two adjacent electrodes 51a, 51b, the metal powder Ms is not electrically connected to each other, so the resistance value between the two electrodes 51a, 51b does not fall below a predetermined value (it is not erroneously detected as the metal powder Ml to be detected).

[0040] In addition, in the conductive particle detection device 14 of this embodiment, the adhesive force of the permanent magnet 3 against the metal powder is set so as to satisfy the above condition (a), so that the entire area surrounding the metal powder Ml to be detected is not completely covered by the lubricating liquid 13, as shown in Figure 4 (B). FIG. 5 is a graph showing the relationship between the iron powder particle size (particle size of metal powder) and the attraction force of the permanent magnet 3. As shown in the graph of FIG. 5, the larger the particle size of the metal powder (iron powder), the stronger the attraction force that the permanent magnet 3 receives, and metal powder with a particle size of 10 μm or more has a much stronger attraction force than metal powder with a particle size of less than 10 μm (particularly, metal powder with a particle size of less than 2 μm). Therefore, the metal powder Ml to be detected receives a large attraction force from the permanent magnet 3. As a result, the metal powder Ml to be detected pushes aside the film of the lubricating liquid 13 and directly contacts each other. Therefore, when the metal powder Ml to be detected is attracted and piled up between the two adjacent electrodes 51a, 51b, the metal powder Ml is in a conductive state, and the resistance value between the two electrodes 51a, 51b becomes a predetermined value or less (the metal powder Ml to be detected is detected).

[0041] Incidentally, the initial wear powder generated when the reducer 10, which is a mechanical operation device, is used for the first time is fine metal powder (metal powder Ms with a minute particle size) with a particle size of less than 10 μm (usually less than 2 μm). Since this metal powder is generated at the beginning of use, it adheres to the surface of the electrodes 51a, 51b and the detection unit cover 24 (see Figs. 2 and 3) of the conductive particle detector 14 as a lower layer at the beginning of use. On the other hand, metal powder (metal powder Ml to be detected) such as wear powder and broken pieces generated during normal use of the reducer 10 inevitably adheres to the upper layer on top of the initial wear powder. Although this metal powder accumulates on the upper side of the initial wear powder, it is reliably attracted even from the upper side of the initial wear powder because its particle size is large and it receives a large attraction force from the permanent magnet 3 as described above. Therefore, the metal powder Ml to be detected generated in the reducer 10 is reliably detected by the conductive particle detector 14.

[0042] <Advantages of the First Embodiment> As described above, in the conductive particle detector 14 of this embodiment, the attraction force of the permanent magnet 3 is set so that the lubricating liquid 13 remains as a non-conductive layer around the metal powder Ms (metal powder with a particle size less than 10 μm) with a particle size smaller than the metal powder Ml (metal powder with a particle size of 10 μm or more) to be detected. Therefore, in the detection gap between the adjacent electrodes 51a, 51b, the lubricating liquid remains as a non-conductive layer around the initial wear powder, which is the metal powder with a particle size of small (metal powder with a particle size less than 10 μm). As a result, even if a predetermined amount or more of the initial wear powder gathers in the detection gap between the adjacent electrodes 51a, 51b, the initial wear powder will not be detected by the detection circuit 50 as the metal powder Ml to be detected. In addition, since the attraction force for the initial wear powder with a small particle size is relatively weak at this time, the amount of the initial wear powder that gathers in the detection gap between the electrodes 51a, 51b is also suppressed to a small amount. Therefore, when the conductive particle detection device 14 of this embodiment is adopted, the expansion of the detection gap between the electrodes 51a, 51b and the expansion of the metal powder collection space can be suppressed, so that the metal powder Ml to be detected can be reliably detected while suppressing the increase in size of the device and the reduction in design freedom.

[0043] <Configuration of the second embodiment> Fig. 6 is a schematic cross-sectional view showing the function of the conductive particle detector 114 of this embodiment. Fig. 6(A) shows a state in which the conductive particle detector 114 adsorbs fine metal powder Ms (initial wear powder) at the beginning of use of the reducer 10 (mechanical operation device), and Fig. 6(B) shows a state in which the conductive particle detector 114 subsequently adsorbs the metal powder Ml to be detected. The conductive particle detector 114 of this embodiment has the same basic configuration as that of the first embodiment, except that the configurations of the electrodes 151a and 151b are different from those of the first embodiment.

[0044] The electrodes 151a, 151b each include a main body 30 made of a conductive permanent magnet 3 and a conductive protruding member 31 (protrusion) attached in contact with the main body 30. The adjacent electrodes 151a, 151b have the same structure except for their polarities. The main body 30 is formed in a substantially rectangular shape and is disposed in the detection window 25 of the detection unit cover 24, similar to the electrodes 51a, 51b of the first embodiment. The flat surface of the main body 30 faces the outside (the space filled with the lubricating liquid 13) through the detection window 25. The main body 30 of each electrode 151a, 151b is electrically connected to the power source 52 and the resistance detection unit 53 of the detection circuit 50.

[0045] The protruding member 31 is fixed to the main surface of the main body 30, which is the surface facing the outside (the space filled with the lubricating liquid), by, for example, a conductive adhesive. The protruding member 31 protrudes outward from a part of the main surface of the main body 30. The cross section of the protruding member 31 in the direction perpendicular to the protruding direction is set to be sufficiently small compared to the main surface of the main body 30. The protruding member 31 in this embodiment is made of a conductive non-magnetic material such as brass, aluminum, copper, etc. Therefore, although the protruding member 31 is provided in contact with the main body 30 made of the permanent magnet 3, it does not directly attract metal powder.

[0046] Furthermore, the magnetic force of the permanent magnet 3 constituting the main body 30 is set so that the minute metal powder Ms (initial wear powder) that adheres to and accumulates on the electrodes 151a, 151b becomes saturated and disperses to the surroundings before it completely covers the protruding member 31. For this reason, as shown in Fig. 6(A), when the minute metal powder Ms in the lubricating liquid 13 gathers and accumulates between the adjacent electrodes 151a, 151b, new metal powder Ms is no longer bound by the magnetic force and disperses into the lubricating liquid before the accumulated metal powder Ms completely covers the protruding member 31.

[0047] In the case of the conductive particle detector 14 of this embodiment, the attraction force acting on the metal powder between the adjacent permanent magnets 3 (electrodes 151a, 151b) is set to satisfy the condition (a) described in the first embodiment. Therefore, the lubricating liquid 13 remains as a non-conductive layer around the minute metal powder Ms (initial wear powder) gathered between the adjacent electrodes 151a, 151b. Therefore, as shown in FIG. 6(A), when only the minute metal powder Ms (initial wear powder) gathers between the adjacent electrodes 151a, 151b, the electrical resistance between the adjacent electrodes 151a, 151b does not become equal to or less than a predetermined value. Therefore, the resistance detector 53 does not erroneously detect that the metal powder Ml to be detected has been generated in an amount greater than the predetermined amount.

[0048] 6B, when the accumulation of initial wear particles (metal powder Ms with a minute particle size) is completed and the metal powder Ml to be detected accumulates between the adjacent electrodes 151a and 151b to a certain extent, the electrodes 151a and 151b are electrically connected by the metal powder Ml to be detected. As a result, the electrical resistance between the electrodes 151a and 151b becomes equal to or less than a predetermined value, and the resistance detector 53 detects the occurrence of the metal powder Ml to be detected. At this time, at least a part of the protruding member 31 of each electrode 151a and 151b protrudes outside the initial wear particles (metal powder Ms with a minute particle size), so that the presence of the metal powder Ml to be detected can be reliably detected.

[0049] <Effects of the second embodiment> As described above, the conductive particle detection device 114 of this embodiment has the same basic configuration as the conductive particle detection device 14 of the first embodiment, and therefore can provide the same basic effects as the conductive particle detection device 14 of the first embodiment.

[0050] In addition, in the conductive particle detector 114 of this embodiment, a conductive protruding member 31 (protrusion) protruding outward from the main surface is attached to the main surface of the main body 30 of the electrodes 151a, 151b on which minute metal powder Ms (initial wear powder) adheres and accumulates. Therefore, even if some minute metal powder Ms (initial wear powder) adheres and accumulates on the main surface of the main body 30 of the electrodes 151a, 151b, at least a part of the conductive protruding member 31 protrudes outward from the accumulated metal powder Ms (initial wear powder). Therefore, when the conductive particle detection device 114 of this embodiment is adopted, it is possible to prevent the conductive parts of the electrodes 151a, 151b from becoming completely buried in fine-grained metal powder Ms (initial wear powder), which would make it impossible for the detection circuit 50 to detect the adhesion of the metal powder to be detected (metal powder with a particle size of 10 μm or more). In the above embodiment, a separate protrusion member 31 is attached to the main body 30 of the electrodes 151a, 151b, which is made of a permanent magnet 3, but it is also possible to integrally form the protrusions protruding from the main surfaces of the electrodes 151a, 151b using the same permanent magnet 3.

[0051] However, in the conductive particle detector 114 of this embodiment, the protruding members 31, which are separate from the main body 30, are made of a nonmagnetic conductor, and therefore the protruding members 31 are not magnetized by the magnetic force of the main body 30 (permanent magnet). This makes it possible to prevent minute metal powder Ms (initial wear powder) from adhering to the protruding members 31 protruding from the main body 30 of the electrodes 151a and 151b. Therefore, when the conductive particle detection device 114 of this embodiment is adopted, it is possible to more reliably prevent the protrusion member 31 from becoming buried in fine grain metal powder Ms (initial wear powder) and being unable to detect the adhesion of the metal powder Ml (metal powder having a grain size of 10 μm or more) to be detected by the detection circuit 50.

[0052] Furthermore, in the conductive particle detector 114 of this embodiment, the magnetic force of the permanent magnet 3 is set so that the minute particle diameter metal powder Ms (initial wear powder) that adheres to and accumulates on the electrodes 151a, 151b is saturated to an extent that does not completely cover the protruding member 31 and disperses into the lubricating liquid 13. This makes it possible to more reliably prevent the conductive parts of the electrodes 151a, 151b from being completely buried in the initial wear powder, which makes it impossible for the detection circuit 50 to detect the adhesion of the metal powder Ml to be detected.

[0053] In addition, when the conductive particle detector 114 of this embodiment is used in a plurality of types of reducers 10 (mechanical operation devices) with different specifications, it is desirable to set the magnetic force of the permanent magnet 3 so that the minute particle size metal powder Ms (initial wear powder) that adheres to and accumulates on the electrodes 151a, 151b in the one with the largest amount of generated metal powder is saturated to the extent that it does not completely cover the protruding member 31. In this case, the common conductive particle detector 114 can be used as it is in all reducers 10 (mechanical operation devices) without changing the settings of the magnetic force of the permanent magnet 3, etc. In other words, if the setting is made so that the protruding members 31 of the electrodes 151a, 151b are not buried in the minute particle size metal powder Ms (initial wear powder) in the reducer 10 (mechanical operation device) with the specifications with the largest amount of attached metal powder, the protruding members 31 of the electrodes 151a, 151b will not be buried in the minute particle size metal powder Ms (initial wear powder) in the reducer 10 (mechanical operation device) with the other specifications with a smaller amount of attached metal powder. Therefore, when this configuration is adopted, the common conductive particle detection device 114 can be used as is with reducers 10 (mechanical operating devices) of multiple specifications, making it possible to produce the conductive particle detection device 114 efficiently.

[0054] <Configuration of the third embodiment> FIG. 7 is a perspective view of a conductive particle detection device 214 of this embodiment, and FIG. 8 is a partial cross-sectional perspective view of the conductive particle detection device 214 shown in FIG. 7 taken along line VIII-VIII. The conductive particle detector 214 of this embodiment has a basic configuration similar to that of the second embodiment, except for the shape of the protruding members 131 constituting part of the electrodes 151a and 151b and the manner in which the protruding members 131 are installed (fixed).

[0055] Each of the electrodes 151a, 151b is composed of a rectangular plate-shaped main body 30 made of a permanent magnet 3, and a protruding member 231 (protrusion) that contacts the main surface (surface facing outward) of the main body 30. The protruding member 231 is formed of a conductive non-magnetic material such as brass, aluminum, or copper. The protruding member 231 has a rectangular plate-shaped extension 32 of a certain width, and a flange portion 33 provided on one end side (hereinafter referred to as the "base side") in the extension direction perpendicular to the width direction of the extension 32. The plate-shaped protruding member 231 is arranged so that the width direction of the extension 32 is aligned with the axial direction of the support block 17, and the end face of the flange portion 33 abuts against the flat main surface of the main body 30.

[0056] In this embodiment, the resin detector cover attached to the outer periphery of the tip side of the support block 17 is composed of a first detector cover 224A on the base side and a second detector cover 224B on the tip side. Both the first detector cover 224A and the second detector cover 224B are formed in a cylindrical shape and are attached to the support block 17 so as to cover the outer periphery side of the support block 17.

[0057] Four substantially rectangular cutouts 41 are formed at equal intervals in the circumferential direction on the edge of the leading end side (the side facing the second detection unit cover 224B) of the peripheral wall 40 of the first detection unit cover 224A. Each cutout 41 is formed at a position that substantially overlaps with the four permanent magnets 3 (the four main body parts 30 of the electrodes 151a and 151b). A slit 41a of a predetermined width is formed in the peripheral wall 40 at a portion corresponding to the bottom of each cutout 41 so as to extend along the axial direction of the first detection unit cover 224A. An extension 32 of the protruding member 231 is fitted into each slit 41a. The extension 32 is fitted into the slit 41a so as to penetrate the slit 41a from the radial inside to the outside of the peripheral wall 40. Further, in the vicinity of each slit 41a in the peripheral wall 40 of the first detection unit cover 224A, a pressing groove 35 is formed by cutting out a flat portion on the inner peripheral surface side of the peripheral wall 40. A part of the flange portion 33 of the protrusion member 131 is fitted into each pressing groove 35. The depth of each pressing groove 35 (the radial depth of the peripheral wall 40) is set so that, with a part of the flange portion 33 fitted into the pressing groove 35, the protrusion member 231 is pressed with sufficient force against the main surface of the main body portion 30 of the electrodes 151a, 15b.

[0058] Four substantially rectangular shielding walls 43 protruding in the axial direction are integrally formed on the edge of the base side (the side facing the first detection unit cover 224A) of the peripheral wall 42 of the second detection unit cover 224B. The four shielding walls 43 are formed at equal intervals in the circumferential direction of the peripheral wall 42. The four shielding walls 43 are inserted into the four cutouts 41 on the first detection unit cover 224A side so as to close the cutouts 41. The edge of the extending end side of each shielding wall 43 is partially hollowed out on the surface facing the main body 30 of the electrodes 151a, 151b. A remaining part of the flange 33 of the protruding member 231 is disposed inside the hollowed out portion.

[0059] Each protruding member 231 of the electrodes 151a, 151b is fixed in contact with the corresponding main surface of the main body 30 (permanent magnet 3) in the following manner, for example. The first detection unit cover 224A and the main body 30 (permanent magnet 3) of the electrodes 151a and 151b are attached in advance to the outer peripheral surface of the tip side of the support block 17. Next, in this state, the extension portion 32 of the protrusion member 231 is fitted into each slit 41a of the first detection unit cover 224A, and a part of the flange portion 33 of the protrusion member 231 is fitted into the pressing groove 35 of the peripheral wall 40. At this time, a part of the flange portion 33 of the protrusion member 231 is pressed radially inward by the pressing groove 35, and the base end (flange portion 33) of the protrusion member 231 is pressed against the main body 30 (permanent magnet 3). As a result, the protrusion member 231 is fixed in contact with the outer surface of the main body 30 (permanent magnet 3) while remaining in an upright position.

[0060] Thereafter, the second detector cover 224B is attached to the outer peripheral surface at the tip end side of the support block 17, and each shielding wall 43 of the second detector cover 224B is inserted into the corresponding notch portion 41 of the first detector cover 224A. At this time, a remaining part of the flange portion 33 of each protruding member 231 is received in the hollowed-out portion of the peripheral wall 42 of the second detector cover 224B. Thereafter, the second detector cover 224B is fixed to the support block 17 by appropriate means such as engagement with a metal engagement piece 45 (see FIG. 8).

[0061] <Effects of the third embodiment> As described above, the conductive particle detection device 214 of this embodiment has the same basic configuration as the conductive particle detection device 114 of the second embodiment, and therefore can provide the same basic effects as the conductive particle detection device 114 of the second embodiment.

[0062] In the conductive particle detection device 214 of this embodiment, the protruding members 231 protruding outward from the main body parts 30 (permanent magnets 3) of the electrodes 151a and 151b are pressed radially inward by the pressing grooves 35 of the first detection unit cover 224A, whereby the protruding members 231 are pressed against the main body parts 30 of the electrodes 151a and 151b. For this reason, when the conductive particle detection device 214 of this embodiment is employed, the contact state between the main body parts 30 of the electrodes 151a and 151b and the protruding members 231 becomes unstable, and a drop in the voltage between the protruding members 231 of the adjacent electrodes 151a and 151b can be suppressed by a simple configuration.

[0063] <Configuration of the Fourth Embodiment> Fig. 9 is a perspective view of a conductive particle detector 314 of this embodiment, and Fig. 10 is a partial cross-sectional perspective view of the conductive particle detector 314 shown in Fig. 9 taken along line XX. Also, Fig. 11 is a cross-sectional view of the conductive particle detector 314 taken along line XI-XI in Fig. 9. The conductive particle detector 314 of this embodiment has a basic configuration that is almost the same as that of the third embodiment. The conductive particle detector 314 of this embodiment differs greatly from that of the third embodiment in the structures of the first detector cover 324A and the second detector cover 324B attached to the outer periphery of the tip side of the support block 17, in particular, in the structures of the engagement parts for the protruding members 231 (protrusions) of the electrodes 151a and 151b.

[0064] As in the third embodiment, each of the electrodes 151a and 151b is made up of a rectangular plate-shaped main body 30 made of a permanent magnet 3, and a protruding member 231 (protrusion) in contact with a main surface (surface facing outward) of the main body 30. The protruding member 231 is made of a conductive non-magnetic material such as brass, aluminum, copper, etc. The protruding member 231 has an extension portion 32 and a flange portion 33.

[0065] The first detection unit cover 324A and the second detection unit cover 324B are both formed in a roughly cylindrical shape, and are attached to the support block 17 so as to cover the outer periphery of the support block 17. Eight dividing slits 65 are formed in the peripheral wall of the first detector cover 324A at intervals in the peripheral direction. Each dividing slit 65 extends from the cylindrical portion 64 in the axial direction toward the tip end side (the side close to the second detector cover 324B), leaving the cylindrical portion 64 on the base side (the side away from the second detector cover 324B) of the first detector cover 324A. The end of each dividing slit 65 opens on the tip end side of the first detector cover 324A. The eight dividing slits 65 divide the area of ​​the peripheral wall of the first detector cover 324A, excluding the cylindrical portion 65a, into eight plate-like pieces extending in the axial direction. Four of the eight plate-like pieces constitute locking pieces 66 that lock the protruding members 231 of the electrodes 151a and 151b. The remaining four of the eight plate-like pieces constitute cover pieces 67 that cover the outside of the support block 17 without engaging the protruding member 231. The locking pieces 66 and the cover pieces 67 are arranged alternately on the outer periphery of the first detection unit cover 324A. Each locking piece 66 is formed at a position that substantially overlaps with the four permanent magnets 3 (the four main bodies 30 of the electrodes 151a, 151b) on the support block 17 in the circumferential direction around the support block 17.

[0066] The four cover pieces 67 are formed in a generally arc-shaped cross section with generally the same diameter (approximately the same inner and outer diameters) as the cylindrical portion 64. In contrast, the four locking pieces 66 are formed in a flat plate-like cross section. The thickness of the locking pieces 66 is set to be thinner than the thickness of the cover piece 67. A slit 68 of a predetermined width is formed in the end face on the tip side in the extension direction of each locking piece 66 so as to run along the axial direction of the first detection unit cover 324A.

[0067] The extending portion 32 of the protruding member 231 is fitted into the slit 68 of each locking piece 66. The extending portion 32 is fitted into the slit 68 so as to penetrate the slit 68 from the radial inside to the radial outside of the locking piece 66. The back surface of the tip side region in the extending direction of the locking piece 66 is made into a pressing surface 69 for pressing down a part of the flange portion 33 of the protruding member 231. When the extending portion 32 of the protruding member 231 is fitted into the slit 68, the pressing surface 69 presses down a part of the flange portion 33 of the protruding member 231 between the pressing surface 69 and the main surface of the main body portion 30 of the electrodes 151a, 151b.

[0068] The gap between the back surface (pressing surface 69) of the locking piece 66 and the main surface of the main body portion 30 facing the locking piece 66 is set to be narrower than the thickness of the flange portion 33. When the extension portion 32 of the protruding member 231 is pressed into the slit 68 of the locking piece 66, the entire locking piece 66 elastically deforms in the plate thickness direction, thereby allowing the flange portion 33 to be inserted into the gap between the locking piece 66 and the main body portion 30.

[0069] The edge of the base side (the side facing the first detection unit cover 324A) of the peripheral wall of the second detection unit cover 324B is partially hollowed out on the surface facing the main body 30 of the electrodes 151a and 151b. A remaining part of the flange portion 33 of the protrusion member 231 is disposed inside the hollowed out portion.

[0070] Each protruding member 231 of the electrodes 151a, 151b is fixed in contact with the main surface of the corresponding main body portion 30 (permanent magnet 3) in the following manner. The first detection unit cover 324A and the main body parts 30 (permanent magnets 3) of the electrodes 151a and 151b are attached to the outer peripheral surface of the tip side of the support block 17. In this state, the extension parts 32 of the protruding member 231 are fitted into the slits 68 of the locking pieces 66 of the first detection unit cover 324A, and a part of the flange part 33 of the protruding member 231 is fitted into the gap between the pressing surface 69 on the tip side of each locking piece 66 and the main body parts 30 of the electrodes 151a and 151b. At this time, the locking pieces 66 are elastically deformed in the plate thickness direction as described above. As a result, a part of the flange part 33 of the protruding member 231 is pressed radially inward by the pressing surface 69, and the base end (flange part 33) of the protruding member 231 is pressed against the main body part 30 (permanent magnet 3). The protruding member 231 is fixed in a contact state with the outer surface of the main body part 30 (permanent magnet 3) while remaining in an upright position.

[0071] Thereafter, the second detector cover 324B is attached to the outer peripheral surface of the tip side of the support block 17. At this time, a remaining part of the flange portion 33 of each protruding member 231 is received in the hollowed-out portion of the second detector cover 324B. Thereafter, the second detector cover 224B is fixed to the support block 17 by appropriate means such as locking with the metal locking piece 45.

[0072] <Effects of the Fourth Embodiment> As described above, the conductive particle detection device 314 of this embodiment has the same basic configuration as the third embodiment, and therefore can provide the same basic effects as the conductive particle detection device 214 of the third embodiment.

[0073] However, in the conductive particle detector 314 of this embodiment, the first detector cover 324A is provided with a locking piece 66 extending in the axial direction, and the locking piece 66 is provided with a slit 68 and a pressing surface 69 for supporting the protruding member 231. Therefore, when the protruding member 231 is sandwiched and fixed between the first detector cover 324A and the main body 30 of the permanent magnets 151a and 151b, the locking piece 66 is elastically deformed in the plate thickness direction, so that the fixing work can be easily performed. Furthermore, when the protruding member 231 is fixed, it is possible to avoid unnecessary distortion of a part of the first detector cover 324A.

[0074] The present invention is not limited to the above-mentioned embodiment, and various design modifications are possible within the scope of the present invention. For example, the conductive particle detection device of the above-mentioned embodiment is applied to a reducer that reduces the rotation speed of the drive source, but the mechanical operating device to which the conductive particle detection device is applied is not limited to a reducer, and may be another operating device that does not have a reduction mechanism as long as the mechanical operating mechanism is housed in a casing. In addition, while the conductive particle detection device in each of the above embodiments detects metal powder generated by a mechanical operating device, if at least a part of the operating mechanism of the mechanical operating device is formed from a conductive material other than metal, it can also detect particles of that conductive material. Furthermore, in the above embodiment, the metal powder (conductive particles) having a particle size of 10 μm or more is set as the metal powder (conductive particles) to be detected, but the metal powder (conductive particles) to be detected may be metal powder (conductive particles) having a particle size of 20 μm or more. In this case, the attraction force of the permanent magnet is set so that the lubricating liquid remains as a non-conductive layer around the metal powder (conductive particles) having a particle size of less than 20 μm. In this way, by changing the attraction force of the permanent magnet, conductive particles of any particle size generated from a mechanical operating device can be detected as the detection target. [Explanation of symbols]

[0075] 3...permanent magnet, 10...reduction gear (mechanical operating device), 11...reduction mechanism part (operating mechanism), 12...casing, 13...lubricating liquid, 14, 114, 214, 314...conductive particle detection device, 30...main body, 31, 131, 231...protruding member (protrusion), 50...detection circuit, 51a, 51b, 151a, 151b...electrodes, 224A, 324A...first detection part cover (detection part cover).

Claims

1. a plurality of electrodes spaced apart in the lubricating liquid; a permanent magnet for collecting conductive particles in the lubricating liquid between adjacent electrodes by magnetic force; A detection circuit that detects conductive particles as a detection target based on the electrical resistance between adjacent electrodes, A conductive particle detection device in which the adhesive force of the permanent magnet acting on the conductive particles between adjacent electrodes is set so that the lubricating liquid remains as a non-conductive layer around the conductive particles having a diameter smaller than that of the conductive particles to be detected, and the conductive particles to be detected come into direct contact with each other, pushing aside the non-conductive layer of the lubricating liquid around the conductive particles.

2. 2. The conductive particle detection device according to claim 1, wherein the conductive particles to be detected have a particle size of 10 [mu]m or more, and the minute particle size is a particle size of less than 10 [mu]m.

3. 3. The conductive particle detection device according to claim 2, wherein the minute particle size is a particle size of less than 2 [mu]m.

4. 4. A conductive particle detection device according to claim 1, wherein the electrode has a conductive protrusion that protrudes partially from a main surface on which the micro-sized conductive particles adhere and accumulate.

5. 5. The conductive particle detector according to claim 4, wherein said protrusion is made of a conductive non-magnetic material.

6. 6. A conductive particle detection device as described in claim 4 or 5, wherein the magnetic force of the permanent magnet is set so that the micro-sized conductive particles that adhere to and accumulate on the electrode become saturated to an extent that does not completely cover the protrusion and disperse into the surrounding area.

7. The conductive particle detection device of claim 6, wherein the magnetic force of the permanent magnet is set so that, in the device that generates the largest amount of conductive particles among multiple types of mechanical operating devices to which it is applied, the fine conductive particles that adhere to and accumulate on the electrode become saturated to an extent that does not completely cover the protrusion and are dispersed into the surrounding area.

8. The protrusion is formed of a protruding member separate from a main body of the electrode, 8. The conductive particle detector according to claim 4, wherein the protruding member is pressed against the main body portion by a detection portion cover that covers a periphery of the main body portion of the electrode.

9. A mechanical operating mechanism; a casing that contains the operating mechanism and a lubricating liquid therein; a conductive particle detector for detecting conductive particles mixed in the lubricating liquid, The conductive particle detection device includes: a plurality of electrodes spaced apart in the lubricating liquid; a permanent magnet for collecting conductive particles in the lubricating liquid between adjacent electrodes by magnetic force; A detection circuit that detects conductive particles as a detection target based on the electrical resistance between adjacent electrodes, A mechanical operating device in which the adhesive force of the permanent magnet acting on the conductive particles between adjacent electrodes is set so that the lubricating liquid remains as a non-conductive layer around the conductive particles having a diameter smaller than that of the conductive particles to be detected, and the conductive particles to be detected come into direct contact with each other, pushing aside the non-conductive layer of the lubricating liquid around the conductive particles.

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