Conductive particle detection device and retarder

Abstract

Provided are a wiring structure, a conductive particle detection device, and a speed reducer. The wiring structure includes a wiring such as a flexible printed wiring board, a permanent magnet, and a relay sheet. The wiring has a through portion. The permanent magnet is conductive. The relay sheet is formed of a conductive metal and is connected to the through portion of the wiring. The relay sheet uses magnetic force to adsorb and fix the permanent magnet.

Description

Technical Field

[0001] The present invention relates to a wiring structure, a conductive particle detection device using the wiring structure, and a speed reducer using the conductive particle detection device. Background Technology

[0002] In devices with built-in mechanical actuators (such as speed reducers), wear on the actuator is reduced by filling the interior of the housing with lubricant. In such devices, metal dust is generated from the mechanical parts during use. This metal dust mixes with the lubricant inside the housing. If a large amount of metal dust is mixed into the lubricant, the wear-inhibiting function of the lubricant on the actuator is reduced. A large amount of metal dust mixed into the lubricant indicates wear and damage to the actuator.

[0003] In the aforementioned apparatus, it is desirable to be able to detect from the outside that the amount of metal powder in the lubricating fluid is above a predetermined amount. As an apparatus for detecting the amount of metal powder from the outside, an apparatus is disclosed that uses a permanent magnet to attract metal powder in the lubricating fluid, thereby enabling electrical detection of the amount of attracted metal powder (for example, see Patent Document 1).

[0004] The detection device (conductive particle detection device) disclosed in Patent Document 1 includes: a cylindrical permanent magnet disposed in a lubricating fluid; and a plurality of electrodes disposed at intervals on the outside of the permanent magnet. The conductive particle detection device is structured to detect the resistance between adjacent electrodes spaced apart, thereby determining the amount of metal powder mixed in the lubricating fluid.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2005-331324 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] In recent years, devices using multiple conductive permanent magnets as electrodes have been proposed as conductive particle detection devices. In these devices, the permanent magnets function as both an attraction part for conductive particles (such as metal powder) and an electrode part. Each permanent magnet is connected to a resistance detection circuit on a detection substrate via wiring.

[0010] The wiring structure connecting the detection substrate and the conductive permanent magnet has a conductive part for connecting the wiring and a corresponding connection means for the permanent magnet. The connection means uses threaded fixing and conductive clamping and locking devices.

[0011] When using threaded fastening as a connection method, a threaded hole needs to be formed in the permanent magnet. However, it is generally difficult to form a high-precision threaded hole in a permanent magnet.

[0012] The clamping and locking device used as a connection means is a large component. Therefore, when using a clamping and locking device as a connection means, the overall wiring structure becomes larger.

[0013] The present invention provides a wiring structure that can easily connect the conductive part of the wiring and the conductive permanent magnet without causing the connection part to become large, a conductive particle detection device, and a speed reducer.

[0014] Solution for solving the problem

[0015] One aspect of the wiring structure of the present invention comprises: a permanent magnet having conductivity; a wiring having a conductive portion; and a repeater plate of a metallic magnetic type connected to the conductive portion, and the permanent magnet being fixed by magnetic attraction.

[0016] Ideally, the wiring should be constructed from a flexible printed wiring board.

[0017] Alternatively, the relay plate and the permanent magnet can be connected by a conductive adhesive.

[0018] One aspect of the conductive particle detection device of the present invention includes: a plurality of permanent magnets arranged separately from each other and having conductivity; a detection substrate that detects conductive particles attracted between adjacent permanent magnets based on the resistance between adjacent permanent magnets; a flexible printed circuit board that electrically connects the detection substrate and each of the permanent magnets; and a plurality of relay plates connected to the conductive portion of the flexible printed circuit board. The plurality of relay plates are of a metallic magnetic material. The plurality of permanent magnets are respectively attracted and fixed to the plurality of relay plates by magnetic force.

[0019] Alternatively, the conductive part and the relay piece can be connected by solder.

[0020] Alternatively, the conductive part and the relay plate can be connected by a conductive adhesive.

[0021] Alternatively, the conductive particle detection device may include a sealing member that seals the lubricant-filled space from the detection space where the detection substrate is disposed. A plurality of permanent magnets are disposed in the lubricant-filled space, which is filled with lubricant. Alternatively, the sealing member may be integrally formed with the flexible printed wiring board.

[0022] One aspect of the present invention provides a speed reducer comprising: a speed reduction mechanism for reducing input rotational speed; a housing for housing the speed reduction mechanism; and a conductive particle detection device for detecting conductive particles of lubricating fluid mixed into the housing. The conductive particle detection device comprises: a plurality of permanent magnets disposed separately within the housing and having conductivity; a detection substrate for detecting conductive particles attracted between adjacent permanent magnets based on the resistance between adjacent permanent magnets; a flexible printed circuit board electrically connecting the detection substrate and each of the permanent magnets; and a plurality of relay plates connected to conductive portions of each of the flexible printed circuit boards. The plurality of relay plates are of a metallic magnetic material. The plurality of permanent magnets are magnetically attracted and fixed to the plurality of relay plates.

[0023] The effects of the invention

[0024] The aforementioned wiring structure comprises a repeater plate with a metallic magnetic material that connects to the conductive portion of the wiring, and a permanent magnet that is magnetically attached to the repeater plate. Therefore, when connecting the conductive portion of the wiring and the conductive permanent magnet, there is no need to perform machining operations on the permanent magnet to form threaded holes. Consequently, by employing the aforementioned wiring structure, the conductive portion of the wiring and the conductive permanent magnet can be easily connected without requiring a large connection portion. Attached Figure Description

[0025] Figure 1 This is a perspective view of the wiring structure according to the first embodiment.

[0026] Figure 2 This is a perspective view showing a part of the manufacturing process of the wiring structure according to the first embodiment.

[0027] Figure 3 This is a partial cross-sectional side view of the reducer on which the conductive particle detection device of the second embodiment is installed.

[0028] Figure 4 This is a partial cross-sectional perspective view of the conductive particle detection device according to the second embodiment.

[0029] Figure 5 This is an enlargement of the conductive particle detection device of the second embodiment. Figure 4 A three-dimensional view of a partial cross-section of the V-section.

[0030] Figure 6 The conductive particle detection device of the second embodiment is along Figure 4 A sectional view along line VI-VI.

[0031] Figure 7 This is a top view of the flexible printed wiring board used in the conductive particle detection device of the second embodiment.

[0032] Explanation of reference numerals in the attached figures

[0033] 1. 101. Wiring structure; 2. 102. Flexible printed wiring board (wiring); 3. Permanent magnet; 4. Repeater; 5. Washer; 10. Reducer; 11. Reducer mechanism; 12. Housing; 13. Lubricating fluid; 14. Conductive particle detection device; 18. Detection substrate; 22. Lubricating fluid filling space; 23. Detection space; 50. Conductive part. Detailed Implementation

[0034] Next, embodiments of the present invention will be described based on the accompanying drawings. Furthermore, in the embodiments described below, common parts are labeled with the same reference numerals, and some repeated descriptions are omitted.

[0035] <First Embodiment>

[0036] Figure 1 This is a perspective view of the wiring structure 1 according to the first embodiment.

[0037] The wiring structure 1 of this embodiment includes: a permanent magnet 3, which is conductive; a flexible printed wiring board (one form of wiring) 2; and a repeater plate of metallic magnetic material 4.

[0038] The permanent magnet 3 is formed as a rectangular plate of a certain thickness. The flexible printed wiring board 2 is formed as a strip. On the flexible printed wiring board 2, a conductive portion (not shown) extends from one end along the long side toward the other end. The conductive portion is covered by a flexible insulating layer 2a. One end and the other end of the conductive portion are exposed outside the insulating layer 2a as terminal portions (not shown).

[0039] A relay plate 4 is connected to one end of the terminal section using solder. Thus, the relay plate 4 is also electrically connected to the conductive portion of the flexible printed circuit board 2. The relay plate 4 is formed of a magnetic material such as metal. A permanent magnet 3 can be magnetically attracted to the relay plate 4. The relay plate 4 is formed into a rectangular plate with a width approximately the same as that of the flexible printed circuit board 2. The front and back surfaces (the surfaces facing the thickness direction) of the relay plate 4 are flat.

[0040] In this embodiment, the relay piece 4 is connected to the terminal portion (conductive portion) of the flexible printed circuit board 2 using solder. However, the relay piece 4 can also be connected to the terminal portion (conductive portion) of the flexible printed circuit board 2 using a conductive adhesive. In this case, the relay piece 4 and the terminal portion of the flexible printed circuit board 2 can be electrically connected using a conductive adhesive. The relay piece 4 is formed as a rectangular plate with a width approximately the same as that of the flexible printed circuit board 2. Therefore, by using an adhesive to fix the surfaces of the relay piece 4 and the flexible printed circuit board 2 facing the thickness direction to each other, the relay piece 4 can be stably fixed to the flexible printed circuit board 2.

[0041] Figure 2 This diagram illustrates the process of connecting the permanent magnet 3 to the repeater 4 after connecting the repeater 4 to the terminal (conducting part) of the flexible printed wiring board 2.

[0042] The permanent magnet 3 is magnetically attracted and fixed to the repeater plate 4, which is connected to the flexible printed wiring board 2. In this embodiment, a conductive adhesive is provided between the permanent magnet 3 and the repeater plate 4. That is, the permanent magnet 3 and the repeater plate 4 are fixed by the magnetic force generated by the permanent magnet 3 and the adhesive force generated by the adhesive.

[0043] The other end of the terminal portion can be connected to a substrate (not shown) having a resistance detection circuit, etc. In this embodiment, a gasket 5, serving as a sealing member, is integrally formed at the midpoint of the long side of the flexible printed wiring board 2. When the wiring structure 1 is installed in a mechanical device such as a speed reducer, the gasket 5 is embedded in a through hole formed in the housing of the mechanical device. The gasket 5 seals the housing and the flexible printed wiring board 2 within the through hole. The flexible printed wiring board 2 is located inside and outside the mechanical device with the through hole through it. In other words, the gasket 5 seals the lubricant filling space (inside the mechanical device) where the permanent magnet 3 is disposed and the substrate placement space (detection space: outside the mechanical device) where the substrate is disposed.

[0044] <Effects of the first embodiment>

[0045] The wiring structure 1 of this embodiment includes: a permanent magnet 3, which is conductive; a flexible printed wiring board 2 (wiring) which has a conductive portion; and a repeater plate 4 of a metallic magnetic type, which is connected to the conductive portion of the flexible printed wiring board 2, and the permanent magnet 3 is fixed by magnetic attraction. Therefore, when connecting the conductive portion of the flexible printed wiring board 2 (wiring) and the permanent magnet 3, the permanent magnet 3 can be attracted and fixed to the repeater plate 4. Therefore, it is not necessary to perform cutting processing on the permanent magnet 3 for forming threaded holes, etc. Therefore, when using the wiring structure 1 of this embodiment, the conductive portion of the flexible printed wiring board 2 (wiring) and the permanent magnet 3 can be easily connected without causing the connection portion to become large.

[0046] In addition to using a flexible printed wiring board 2, the wiring that electrically connects the permanent magnet 3 and the substrate can also use covered wires with circular or rectangular cross-sections.

[0047] However, when a flexible printed wiring board 2 is used as the wiring to electrically connect the permanent magnet 3 and the substrate in the wiring structure 1 of this embodiment, the wiring can be freely wound even in a narrow configuration space, and the wiring shape can be stabilized. The flexible printed wiring board 2 has a flat surface, so the repeater 4 can be stably supported on the flat surface of the flexible printed wiring board 2.

[0048] In the wiring structure 1 of this embodiment, the relay plate 4 and the permanent magnet 3 are also connected by a conductive adhesive. Therefore, in addition to utilizing the adsorption force of the permanent magnet 3, the adhesive force of the conductive adhesive can also be used to firmly fix the permanent magnet 3 to the relay plate 4. When actually connecting the permanent magnet 3 and the relay plate 4, it is only necessary to apply a conductive adhesive to at least one of the relay plate 4 and the permanent magnet 3 in advance, and in this state, the permanent magnet 3 can be attracted to the relay plate 4 by magnetic force. Therefore, the manufacturing of the wiring structure 1 does not become complicated.

[0049] In the wiring structure 1 of this embodiment, a flat surface is formed on the repeater plate 4. A permanent magnet 3 is adsorbed and fixed on the flat surface of the repeater plate 4. Therefore, with this structure, the electrical connection and mechanical fixation between the repeater plate 4 and the permanent magnet 3 can be made stable.

[0050] When the repeater 4 is connected to the conductive part of the flexible printed wiring board 2 (wiring) using a conductive adhesive, even if the repeater 4 and the conductive part of the flexible printed wiring board 2 (wiring) are made of materials and structures that are difficult to connect with solder, the repeater 4 and the conductive part of the flexible printed wiring board 2 (wiring) can be stably connected in a conductive state.

[0051] <Second Implementation>

[0052] Figure 3 This is a partial cross-sectional side view of the reducer 10 according to the second embodiment.

[0053] The reducer 10 includes a reduction mechanism 11 that reduces the input rotational speed at a predetermined reduction ratio, and a housing 12 that houses the reduction mechanism 11. The housing 12 is filled with a lubricant 13 for lubricating the reduction mechanism 11 and other mechanical contact parts. A conductive particle detection device 14 is installed on the wall 12a of the housing 12. The conductive particle detection device 14 detects conductive particles such as metal powder mixed into the lubricant 13.

[0054] Figure 4 This is a perspective view of a portion of the conductive particle detection device 14 as a longitudinal section along its long side. Figure 5 yes Figure 4 An enlarged view of the V-shaped part. Figure 6 It is along Figure 4A sectional view along line VI-VI.

[0055] The conductive particle detection device 14 includes: a generally cylindrical device body 16; a support block 17 fixed inside the device body 16; and a flexible printed wiring board 102 (wiring) supported on the support block 17. The conductive particle detection device 14 includes: four permanent magnets 3 connected to one end of the flexible printed wiring board 102 along its long side via relay plates 4; and a detection substrate 18 connected to the other end of the flexible printed wiring board 102 along its long side. The permanent magnets 3, the flexible printed wiring board 102, and the relay plates 4 constitute the wiring structure 101 in this embodiment.

[0056] The device body 16 is mounted on the housing 12 of the reducer 10 (see reference). Figure 3 A threaded hole penetrating the wall 12a is formed in the wall 12a of the housing 12. The device body 16 is made of metal, for example. The device body 16 includes a cylindrical retaining sleeve 16a and a flange portion 16b. The retaining sleeve 16a is screwed into and fixed to the threaded hole formed in the wall 12a. Thus, the device body 16 is installed with the wall 12a penetrating through it. The flange portion 16b is integrally formed at the other end of the retaining sleeve 16a (the end on the side disposed on the outside of the housing 12).

[0057] An external thread 19 is formed on the outer peripheral surface of the fixed cylinder 16a. The external thread 19 is screwed into the threaded hole of the wall 12a. A bottomed cylindrical device cover 20 is provided on the outer side of the flange portion 16b. The device cover 20 is fixed to the outer end face of the flange portion 16b (facing the end face opposite to the housing 12) by bolts 21 (fastening members). The device cover 20 and the flange portion 16b are sealed by a circular plate-shaped washer 5 (sealing member). The washer 5 and the insulating layer 102a of the flexible printed wiring board 102 (see reference) Figure 7 The flexible printed wiring board 102 is integrally formed with the gasket 5 in a manner that the gasket 5 extends through the gasket 5 in the thickness direction.

[0058] A detection base plate 18 is mounted on the outer end face of the gasket 5 (the end face facing the side opposite to the housing 12). The detection base plate 18 is covered by the device cover 20. The outer periphery of the gasket 5 is fixed to the device cover 20 and the flange 16b in a state where it is held between the device cover 20 and the flange 16b. The gasket 5 fills the lubricant-filled space 22 inside the housing 12 (see reference). Figure 3 It is sealed between the detection space 23 (the space inside the device cover 20) where the detection substrate 18 is configured.

[0059] The support block 17 is formed of resin material into a hollow quadrangular prism shape. The other end of the support block 17 along its long side (hereinafter referred to as the "base") is fixed to the inside of the device body 16. The support block 17 is arranged along the axial direction of the fixing cylinder 16a. One end of the support block 17 along its long side (hereinafter referred to as the "top") protrudes outward relative to the fixing cylinder 16a of the device body 16 (inside the housing 12).

[0060] The outer peripheral surface and top surface of the top end of the support block 17 are covered by a bottomed cylindrical detection cover 24. The detection cover 24 is integrally formed of resin material. The detection cover 24 includes: a peripheral wall 24a having four detection windows 25; and an end wall 24b that blocks the axial ends of the peripheral wall 24a. The four detection windows 25 of the peripheral wall 24a are equally spaced at approximately 90° intervals on the outer periphery of the peripheral wall 24a. Each detection window 25 is formed to be approximately rectangular in shape from the main view. The edges constituting the edges of each detection window 25, on both sides along the circumferential direction of the peripheral wall 24a, are formed as conical surfaces 25a. The conical surfaces 25a are formed such that the opening area of ​​the detection window 25 increases radially outward.

[0061] The end wall 24b of the detection cover 24 is riveted to the top surface of the support block 17. Reference numeral 26 in the figure is a rivet used to fix the detection cover 24 to the support block 17.

[0062] Figure 7 This is a top view of the flexible printed wiring board 102.

[0063] like Figure 7 As shown, the flexible printed circuit board 102 of this embodiment has a base 102b and four branch portions 102c branching from the base 102b. A washer 5 passes through the base 102b in the thickness direction. A conductive portion 50 is formed on the flexible printed circuit board 102 from the base 102b toward the top of each branch portion 102c. At the other end (terminal portion) of the conductive portion 50, a detection substrate 18 is connected to the outside of the housing 12. The four branch portions 102c branching from the base 102b are respectively arranged along the four sides of the outer periphery of the support block 17. Support grooves 27 (see reference) are formed on the four sides of the outer periphery of the support block 17 in a manner along the long side direction of the support block 17. Figure 6 Each branch 102c is supported by the support groove 27 on each side of the support block 17.

[0064] At one end of the conductive section 50, a relay plate 4 is connected to the top of each branch 102c. The relay plate 4 is formed of a metallic magnetic material and is generally rectangular in shape. The relay plate 4 is connected to the conductive section 50 by a conductive adhesive and solder. Each relay plate 4 is supported together with the branch 102c in the support groove 27 on the top side of the support block 17.

[0065] The surface of each relay plate 4 facing the side opposite to the support block 17 (hereinafter referred to as the surface) is formed as a flat surface. A corresponding permanent magnet 3 is magnetically attached to the surface of each relay plate 4. In this embodiment, each permanent magnet 3 may also be attached to the relay plate 4 using a conductive adhesive.

[0066] After the relay plate 4 and the permanent magnet 3 are mounted on the outer periphery of the support block 17, the detection cover 24 is mounted on the top end of the support block 17. The detection cover 24 is aligned such that the four corresponding permanent magnets 3 are located inside the four detection windows 25 (radially inside the peripheral wall 24a). In this state, the detection cover 24 is riveted to the top end of the support block 17. At this time, the end face of the peripheral wall 24a of the detection cover 24 (the end face on the side opposite to the end wall 24b) abuts against the end face of the fixing cylinder 16a of the device body 16.

[0067] The top end of the conductive particle detection device 14 passes through the threaded hole in the wall 12a and is inserted into the housing 12. In this state, the fixing sleeve 16a of the conductive particle detection device 14 is screwed into the threaded hole. Thus, the conductive particle detection device 14 is fixed to the housing 12. If lubricating fluid 13 is filled into the housing 12 in this state, the plurality of permanent magnets 3 and the detection cover 24 are immersed in the lubricating fluid 13.

[0068] The detection substrate 18 includes a resistance detection circuit. The resistance detection circuit detects the resistance between a plurality of adjacent permanent magnets 3 on the outer periphery of the support block 17. The plurality of permanent magnets 3 are as follows: Figure 6 As shown, they are separated from each other. Therefore, in the initial state of being immersed in the lubricating fluid 13, the resistance between adjacent permanent magnets 3 becomes infinite. If, from this state onwards, the amount of conductive particles (such as metal powder) mixed into the lubricating fluid 13 increases due to the use of the reducer 10, the conductive particles mixed into the lubricating fluid 13 are attracted by the multiple permanent magnets 3 of the conductive particle detection device 14. The attracted conductive particles are adsorbed onto the surface of each permanent magnet 3 through the detection window 25 of the detection cover 24, and are also adsorbed onto the outer peripheral surface of the detection cover 24 by the magnetic force of the permanent magnets 3.

[0069] If the amount of conductive fluid mixed into the lubricating fluid 13 increases, the amount of conductive particles adsorbed on the outer peripheral surface of the detection cover 24 also increases with the increase in the amount mixed. If the amount of conductive particles adsorbed increases to a certain amount, the resistance value between adjacent permanent magnets 3 decreases to below a specified value. The detection board 18 detects that the resistance value has decreased to below the specified value. The detection board 18 is connected to a display device and a warning device via a controller. Thus, operators can determine whether the amount of conductive particles in the reducer 10 has increased to a specified amount or more through the display device, warning device, etc.

[0070] <Effects of the Second Embodiment>

[0071] As described above, the conductive particle detection device 14 of this embodiment includes: a plurality of conductive permanent magnets 3 arranged separately from each other; a detection substrate 18; a flexible printed circuit board 2 connecting the detection substrate 18 and each permanent magnet 3; and a metal magnetic relay plate 4 connected to the conductive portion 50 of the flexible printed circuit board 2 on the side near the permanent magnet 3, thereby magnetically adsorbing and fixing the permanent magnets 3. The conductive particle detection device 14 of this embodiment can magnetically adsorb and fix the conductive permanent magnets 3 to the relay plate 4. Therefore, when connecting the conductive portion 50 of the flexible printed circuit board 2 and the conductive permanent magnets 3, it is not necessary to perform cutting processing on the permanent magnets 3 for forming threaded holes, etc. Therefore, by using the conductive particle detection device 14 of this embodiment, the conductive portion 50 of the flexible printed circuit board 2 and the conductive permanent magnets 3 can be easily connected without causing the connection portion to become large.

[0072] In this embodiment, the conductive particle detection device 14 can firmly fix the metal magnetic relay 4 to the conductive part 50 of the flexible printed circuit board 102 when the conductive part 50 and the relay piece 4 are connected by solder.

[0073] In this embodiment, the conductive particle detection device 14 connects the conductive portion 50 of the flexible printed wiring board 102 and the relay piece 4 using a conductive adhesive. Even if the relay piece 4 and the conductive portion 50 of the flexible printed wiring board are made of materials or structures that are difficult to fix with solder, the relay piece 4 can be stably fixed to the conductive portion 50 of the flexible printed wiring board 102 in a conductive state.

[0074] In the conductive particle detection device 14 of this embodiment, a flexible printed wiring board 102 is used as the wiring to electrically connect the permanent magnet 3 and the detection substrate 18. Therefore, even in the relatively narrow arrangement space within the conductive particle detection device 14, the wiring can be freely wound, and the wiring shape can be stabilized.

[0075] In this embodiment, the conductive particle detection device 14 has a gasket 5 (sealing member) integrally formed on the flexible printed wiring board 102 to seal the lubricant filling space 22 of the reducer 10 filled with lubricant 13 and the detection space 23 on which the detection substrate 18 is disposed. Therefore, it is a structure that is easy to manufacture and assemble, and can reliably prevent lubricant 13 from flowing into the detection space 23.

[0076] Furthermore, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from its spirit.

Claims

1. A conductive particle detection device, comprising: Multiple permanent magnets that are conductive are arranged separately from each other; A detection substrate that detects conductive particles attracted between adjacent permanent magnets based on the resistance between them. Wiring that electrically connects the detection substrate and each of the permanent magnets; and A repeater plate with a metallic magnetic structure is connected to the conductive portion of each of the wirings on the side near the permanent magnet, and the permanent magnet is fixed to the repeater plate by magnetic attraction.

2. The conductive particle detection device according to claim 1, wherein, The wiring is made of a flexible printed wiring board.

3. The conductive particle detection device according to claim 2, wherein, The conductive section and the relay plate of the flexible printed wiring board are connected by solder.

4. The conductive particle detection device according to claim 2, wherein, The conductive portion and the relay plate of the flexible printed wiring board are connected by a conductive adhesive.

5. The conductive particle detection device according to any one of claims 2 to 4, wherein, A sealing member is integrally formed on the flexible printed wiring board, which seals the lubricant filling space from the detection space where the detection substrate is disposed, and a plurality of permanent magnets are disposed in the lubricant filling space.

6. A speed reducer, comprising: The speed reduction mechanism reduces the input rotation speed; A housing that internally houses the reduction gear mechanism; and A conductive particle detection device that detects conductive particles in the lubricating fluid mixed into the housing. The conductive particle detection device includes: Multiple conductive permanent magnets are arranged separately from each other inside the housing; A detection substrate that detects conductive particles attracted between adjacent permanent magnets based on the resistance between them. Wiring that electrically connects the detection substrate and each of the permanent magnets; and A repeater plate with a metallic magnetic structure is connected to the conductive portion of each of the wirings on the side near the permanent magnet, and the permanent magnet is fixed to the repeater plate by magnetic attraction.

7. The reducer according to claim 6, wherein, The wiring is made of a flexible printed wiring board.

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