JP2018163133A - Sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve abrasion powder detection sensitivity by increasing the amount of abrasion powder that accumulates in a detection region.SOLUTION: A sensor is configured to attract magnetic powder floating in lubricant to a space between electrodes by means of a magnetic field applied across the electrodes, and to detect reduction in electrical resistance between electrodes. At least a portion of the space between the electrodes is designated as a detection region in which the magnetic powder can be collected, and the space outside the detection region around the electrodes is designated as non-detection region in which collection of the magnetic powder is suppressed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a sensor.

  In a mechanical device such as a speed reducer, lubricating oil is stored in a housing that accommodates mechanical parts in order to prevent damage to mechanical parts such as gears and bearings. In the lubricating oil, wear powder (mainly iron powder) is mixed due to wear of machine parts during operation of the mechanical device.

  Generally, when wear of a machine part progresses and the wear failure period in the failure rate curve (bathtub curve) starts, the amount of wear powder mixed into the lubricating oil (the amount of wear powder generated in the machine part) increases. In order to perform preventive maintenance, it is necessary to detect an increase in the amount of wear powder generated at an appropriate timing.

  For example, Patent Document 1 describes a sensor that detects the amount of metal powder in oil. The sensor described in Patent Document 1 includes a sensor head portion having a permanent magnet, a cup-shaped electrode provided on the tip surface of the sensor head portion, and a plurality of rod-shaped conductors arranged side by side on the outer peripheral surface of the sensor head portion. I have. When wear powder accumulates between the opposing end surfaces (detection regions) of the rod-shaped conductor to which the magnetic field is applied by the permanent magnet and the cup-shaped electrode, and the conductor is short-circuited, the output of the sensor changes. In Patent Document 1, it is possible to detect the degree of oil contamination by changing the output of the sensor.

JP 2005-331324 A

  In the sensor of Patent Document 1, magnetic flux leaks to the surrounding space other than the detection area, and wear powder accumulates in places other than the detection area. Therefore, the wear powder accumulated in the detection area decreases, and the detection sensitivity decreases. There is a problem of end up.

  The present invention has been made in view of the above circumstances, and an object thereof is to improve the sensitivity with which the sensor detects magnetic powder by efficiently accumulating magnetic powder such as wear powder in the detection region. It is to let you.

  A sensor according to an embodiment of the present invention applies a magnetic field between electrodes, accumulates magnetic powder containing magnetic powder floating in lubricating oil between the electrodes, and detects a decrease in electrical resistance between the electrodes. The sensor is provided with a detection region capable of accumulating magnetic powder in at least a part between the electrodes, and accumulation of magnetic powder is suppressed in a non-detection region that is a space around the electrode other than the detection region. Features.

  In the above sensor, the detection region includes a first electrode and a second electrode, wherein a gap is provided between the first electrode and the second electrode, and a magnetic field is applied to at least a part of the gap. It is good also as a structure provided.

  In the above sensor, the first electrode may be a magnet that generates a magnetic field.

  The sensor may further include a magnet that generates a magnetic field.

  In the above-described sensor, the non-detection region may include a non-magnetic covering member that covers the electrode and suppresses the accumulation of magnetic powder.

  In the above sensor, the entire circumference of the magnet may be covered with a magnet covering member.

  In the above sensor, a magnetic field may be selectively applied to the detection region.

  The above sensor may have a configuration in which a plurality of detection regions are provided.

  The sensor has a first detection region and a second detection region, the first detection region is provided adjacent to the N pole of the magnet, and the second detection region is provided adjacent to the S pole of the magnet. It is good also as a structure.

  The sensor may include a plurality of second electrodes, a gap portion provided between the plurality of second electrodes and the first electrode, and a detection region provided in each gap portion.

  In the above sensor, the gap lengths may be different in the plurality of detection regions.

  In the above sensor, a plurality of electrode pairs of the first electrode and the second electrode may be provided, and the plurality of electrode pairs may have different gap lengths.

  In the above sensor, a configuration may be adopted in which a recess having a narrow width is provided on the outer peripheral portion, and a detection region is provided in the back of the recess.

  The sensor may include a filter member that is disposed between the detection region and the external space and prevents passage of a foreign substance having a large particle diameter.

  The above sensor may be configured so that the magnetic flux does not leak from the detection region to the outside.

  In the above sensor, the detection region is a region sandwiched between a first plane formed on the first electrode and a second plane formed parallel to the first plane formed on the second electrode, A configuration in which the magnetic flux intersects the first plane and the second plane perpendicularly in the detection region may be adopted.

  According to one embodiment of the present invention, since accumulation of magnetic powder is suppressed in the non-detection area, it is possible to efficiently accumulate magnetic powder in the detection area, and as a result, the detection sensitivity of the sensor is improved. Therefore, it is possible to reliably detect (with high reliability) an increase in the amount of wear powder generated.

It is a side view of the industrial robot which concerns on one Embodiment of this invention. It is sectional drawing which shows the structure of the joint part with which the industrial robot which concerns on one Embodiment of this invention is equipped, and its periphery. It is a figure which shows the structure of the sensor which concerns on Example 1 of this invention. It is a figure which shows the structure of the sensor which concerns on Example 2 of this invention. It is a figure which shows the structure of the sensor which concerns on Example 3 of this invention. It is a figure which shows the structure of the sensor which concerns on Example 4 of this invention. It is a figure which shows the structure of the sensor which concerns on Example 5 of this invention. It is a figure which shows the structure of the sensor which concerns on Example 6 of this invention. It is a figure which shows the structure of the sensor which concerns on Example 7 of this invention. It is a figure which shows the structure of the sensor which concerns on Example 8 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Hereinafter, as an embodiment of the present invention, an industrial robot will be described as an example.

  FIG. 1 is a side view of an industrial robot 1 according to an embodiment of the present invention. The industrial robot 1 is a 6-axis vertical articulated robot.

  As shown in FIG. 1, the industrial robot 1 includes an attachment portion 11 for attaching the industrial robot 1 to a floor, a wall, a ceiling, or the like, arms A1 to A5, and joint portions J1 to J6. The joint portion J1 movably connects the attachment portion 11 and the arm A1. The joint J2 movably connects the arm A1 and the arm A2. The joint J3 movably connects the arm A2 and the arm A3. The joint J4 movably connects the arm A3 and the arm A4. The joint portion J5 movably connects the arm A4 and the arm A5. A handpiece (not shown) is attached to the tip of the industrial robot 1 (tip of the joint J6).

  Each joint part J1-J6 is provided with the servomotor for driving, and the reduction gear, respectively. Since the basic configurations of the joint portions J1 to J6 are common, the specific configuration of the joint portion J2 will be described below on behalf of the joint portions J1 to J6, and the details of the joint portions J1, J3 to J6 will be described below. The description of is omitted.

  FIG. 2 is a partial cross-sectional view showing a configuration of the joint portion J2 and its surroundings. As shown in FIG. 2, the joint portion J <b> 2 includes a flange 10, a speed reducer 20, and a servo motor 30.

  The flange 10 is a frame of the joint portion J <b> 2, and the case of the speed reducer 20 and the servo motor 30 is attached to the flange 10. The flange 10 is fixed to the arm A1. The flange 10 is a substantially cylindrical member having a hollow portion (space S). The openings at both ends in the axial direction of the flange 10 are closed by the speed reducer 20 and the servo motor 30, respectively, and a sealed space S is formed. The space S is filled with lubricating oil, and the flange 10 also functions as an oil bath.

  The speed reducer 20 includes a case 206 attached to the flange 10, an input shaft 202 connected to the output shaft 31 of the servo motor 30, and an output shaft 204 fixed to the arm A2. The input shaft 202 and the output shaft 204 are supported so as to be rotatable around the rotation axis AX with respect to the case 206. The output of the servo motor 30 is input to the speed reducer 20 via the input shaft 202, and after being decelerated by the speed reducer 20, it is transmitted to the arm A2 via the output shaft 204. With this configuration, when the servomotor 30 is rotationally driven, the arm A2 is rotationally driven around the rotational axis AX with respect to the arm A1.

  A space in the case 206 in which the gear mechanism of the speed reducer 20 is accommodated communicates with a space S in the flange 10. When the speed reducer 20 is operated, the lubricating oil circulates between the space in the case 206 and the space S in the flange 10 as the gear mechanism in the case 206 rotates. Due to the circulation of the lubricating oil, the wear powder generated inside the speed reducer 20 is discharged into the space S in the flange 10.

  In the space S, a sensor 40 for detecting an increase in wear powder floating in the lubricating oil is attached to the support member 214. The sensor 40 is a sensor that accumulates wear powder in a gap portion between electrodes using a magnet and detects the amount of wear powder in the lubricating oil based on a change in electrical resistance between the electrodes. A plurality of variations are conceivable for the sensor 40. 3 to 10 illustrate some of the variations of the sensor 40. The sensor 40 may be disposed in the case 206.

[Example 1]
FIG. 3 is a diagram illustrating a configuration of the sensor 40A according to the first embodiment of the present invention. 3A to 3C are a plan view, a right side view, and a front view of the sensor 40A, respectively. FIG.3 (d) is sectional drawing in the _AA - _AA line of Fig.3 (a). Figure 3 (e) is a cross-sectional view in _B A -B _A line in FIG. 3 (c). In the following description, the horizontal direction in FIG. 3E is referred to as the X-axis direction, the vertical direction is referred to as the Y-axis direction, and the vertical direction in FIG. 3D is referred to as the Z-axis direction (height direction, axial direction). In FIG. 3D, the upper side (Z-axis positive direction) is referred to as the upper side, and the lower side (Z-axis negative direction) is referred to as the lower side. Note that the sensor 40A may be directed in any direction in the vertical direction during use.

  As shown in FIG. 3, the sensor 40A includes a permanent magnet 402A, a box-shaped electrode (electrode) 406A, a holding member 408A, and a jacket member 410A. As shown in FIG. 3D, the signal line 41 is connected to the box electrode 406A, and the signal line 42 is connected to the permanent magnet 402A. Thereby, permanent magnet 402A serves as a magnet and an electrode.

  The box-like electrode 406A is a magnetic member formed of a magnetic material having conductivity, such as iron, a ferrite core, or silicon steel. Although the box-shaped electrode 406A is substantially cylindrical, the opening on one end side (the lower side in FIG. 3) in the axial direction is closed by the bottom 406Aa and has an opening on the upper surface. Yes. The shape of the box-shaped electrode 406A is not limited to the box shape, but may be an electrode having a rectangular parallelepiped shape in which only the upper surface is opened or a polygonal tube shape having the lower surface closed. Further, the electrode 406A may be nonmagnetic copper or the like.

  A resin-made holding member 408A (covering member), which is a non-magnetic material (insulator), is disposed in the hollow portion of the box-shaped electrode 406A. A permanent magnet 402A is embedded in the upper center of the holding member 408A.

  That is, the box-shaped electrode 406A is disposed at a position surrounding the holding member 408A in which the permanent magnet 402A is embedded. The shape of the permanent magnet 402A is not limited to a rectangular parallelepiped shape, but may be other shapes such as a cylindrical shape or a polygonal column shape.

As shown in FIG. 3E, the outer shape of the permanent magnet 402A is smaller than the inner periphery of the box-shaped electrode 406A. Therefore, between the permanent magnets 402A and box-shaped electrodes 406A, along the entire circumference of the permanent magnets 402A (the position to surround take permanent magnet 402A) gap _{G A} is formed. In other words, the permanent magnets 402A and box-shaped electrodes 406A are opposed via a gap _{G A.}

  The permanent magnet 402A also functions as an electrode. Output lines (signal lines 41 and 42 shown in FIGS. 2 and 3) are connected to the permanent magnet 402A and the box-shaped electrode 406A. For example, another electrode made of a magnetic material may be attached to the upper surface of the permanent magnet 402A. The permanent magnet 402A may be a magnet or an electromagnet, and the magnet may be covered with a nonmagnetic material such as copper and the signal line 42 may be connected to the copper.

The output end of the output line is connected to a sensor drive circuit (not shown) that monitors the resistance value of the sensor 40A and determines the deterioration of the lubricating oil from the fluctuation of the resistance value. Abrasion powder above a certain amount is accumulated in the gap G _A (the gap G _A is schematically is filled with abrasion powder), the electrical resistance between the permanent magnet 402A and the box-shaped electrode 406A is lowered ( The output level of the output line changes. The sensor driving circuit detects the deterioration of the lubricating oil based on the decrease in the electrical resistance. In addition, the decrease in electrical resistance includes an on / off signal due to non-energization and conduction, and detection may be performed in two states, de-energization and energization (hereinafter referred to as “digital detection”).

  The sensor driving circuit is connected to a host control device such as a manipulator by wire or wireless. The circuit board 43 may always transmit the output of the output line (the output of the sensor 40A) to the host controller, and intermittently (every predetermined time interval) to the host controller for power saving. May be.

  When detecting the change in the output level of the output line received from the circuit board 43, the host controller issues, for example, a warning prompting maintenance of the speed reducer 20 by a predetermined notification means (display device or sound output device).

Permanent magnet 402A is magnetized in the arrow _{M A} direction in FIG. 3 (d). Therefore, the magnetic flux path phi _A shown in FIG. 3 (d) are formed. _A strong magnetic flux flows in a region located on the magnetic flux path in the gap portion GA over the entire circumference of the permanent magnet 402A. Further, a strong magnetic flux also flows in a region located in the vicinity of the S and N magnetic poles of the permanent magnet 402A. Hereinafter, for convenience of explanation, this area is referred to as a “detection area”, and the detection area in the first embodiment is denoted by “G _A ”.

The gap G _A, by the magnetic force of the permanent magnet 402A, the abrasion powder of the machine parts were mixed into the lubricant is adsorbed. Abrasion powder, in particular, are adsorbed to the detection region D _A strong magnetic flux flow. _A stable amount (for example, an amount roughly proportional to the amount mixed in the lubricating oil) is adsorbed on the detection region DA.

Of gap G _A, a region other than the detection area D _A (hereinafter, referred to as "non-detection region".), The distance between the permanent magnet 402A is far away. For this reason, almost no magnetic flux flows in the non-detection region that is far from the permanent magnet 402A, and the wear powder is hardly adsorbed.

Thus, in the first embodiment, by the permanent magnets 402A and gap G _A is disposed at an appropriate positional relationship, limited area within the gap G _A is set as the detection area D _A Yes. Since wear powder is intensively adsorb the detection area D _A where adsorption amount is stabilized, the output of the sensor 40A is stabilized. Therefore, the host control device can detect (with high reliability) an increase in the amount of wear powder generated. Even in the case of digital detection, it is possible to detect the increase in the amount of wear powder generated and to be energized to transmit a detection signal.

To Fugen, of gap G _A, the magnetic flux as the region away from the detection area D _A is weakened, the adsorption amount of abrasion powder is not stable. In other words, typically, an amount of wear powder that is not proportional to the amount mixed into the lubricating oil is adsorbed in such a region. The abrasion powder adsorbed in the non-detection region can be a noise for the sensor 40A because the adsorbed amount is unstable.

Therefore, in the present embodiment, the resin of the jacket member 410A (covering member) is attached by an adhesive or the like to the upper surface of the gap portion G _A. Jacket member 410A, of the gap _{G A,} is exposed only to the appearance detection area _{D A.} In other words, the jacket member 410A, of the gap _{G A,} cover the non-detection region.

By attaching the jacket member 410A on the upper surface of the gap portion G _A, (more precisely, the surface of the jacket member 410A located above of the area) non-detection region in, the distance between the permanent magnets 402A farther away. Therefore, the wear powder is hardly adsorbed on the outer surface of the jacket member 410A, which is separated from the permanent magnet 402A. Thus, in the first embodiment, the adsorption area of the wear particles is substantially limited to the detection area D _A.

In the present embodiment, the upper surface of the permanent magnet 402A and the upper end surface of the box electrode 406A are arranged on the same plane. The sensor 40A, the shape of the permanent magnets 402A and a box-shaped electrode 406A, the size, the arrangement, etc., the magnetic flux phi _A is configured to flow parallel to the upper surface of the permanent magnet 402A in the gap _{G A.} Therefore, the magnetic flux phi _A is without hardly leaks to the outside of the sensor 40A off the flux path phi _A, the abrasion powder, the non-detection area such as the outer surface of the sensor 40F (a portion other than the detection region D _A) is without accumulating constrained to the flux phi _a solely the detection area D _a are integrated.

[Example 2]
FIG. 4 is a diagram illustrating a configuration of a sensor 40B according to the second embodiment of the present invention. 4 (a) and 4 (b) are a plan view and a front view of the sensor 40B, respectively. 4 (c) is a sectional view taken along _A B -A _B line in FIG. 4 (a). FIG. 4 (d) is a sectional view taken along _B B -B _B line in Figure 4 (b). In the following embodiments, the description of the same contents as those in the previous embodiments will be simplified or omitted as appropriate.

  As shown in FIG. 4, the sensor 40B includes a permanent magnet 402B, a box-shaped electrode 404B (first electrode), a box-shaped electrode 406B (second electrode), and a holding member 408B (magnet covering member). As shown in FIG. 4C, the signal line 41 is connected to the box electrode 404B, and the signal line 42 is connected to the box electrode 406B. You may make it suppress the accumulation | storage of the said magnetic powder with the coating | coated member for magnets.

  Each of the box-shaped electrodes 404B and 406B is a cylindrical member in which an opening on one end side in the axial direction is closed (in other words, only the other end is opened). The box-shaped electrode 404B is disposed with the opening facing the box-shaped electrode 406B. The box-shaped electrode 406B is disposed concentrically so that the opening faces the box-shaped electrode 404B and the box-shaped electrode 404B faces the opening.

  The holding member 408B is formed in a cylindrical shape having an outer diameter slightly smaller than the inner diameters of the box-shaped electrodes 404B and 406B, and is accommodated in the hollow portions of the box-shaped electrode 404B and the box-shaped electrode 406B. It is arranged in a space defined by the inner wall surface.

The box-shaped electrode 404B and the box-shaped electrode 406B are arranged such that their annular facing surfaces (indicated by reference numerals 404Bc and 406Bc in FIG. 4C) are separated by a predetermined amount. By opposing surfaces is spaced, annular gap G _B surrounding the axial central portion of the holding member 408B between the facing surfaces are formed.

Permanent magnet 402B is, S poles and N poles are arranged in an arrow _{M B} direction in FIG. 4 (c). Permanent magnet 402B is buried in the holding member 408B in a posture straight line connecting the magnetic poles intersects the central axis perpendicular to and gap G _B of the holding member 408B. Therefore, of the holding member 408B side all around over a gap G _B, black filled areas in FIG. 4 (c) and FIG. 4 (d) is selectively a magnetic field is applied, this embodiment 2 is a detection area. Hereinafter, this detection area is referred to as “detection area D _B ”.

Non-detection region other than the detection area D _B is located away from the magnetic poles of and the permanent magnet 402B not located on the magnetic flux path. Therefore, although flows detection area D strong magnetic flux in _B, and the non-detection region, almost the magnetic flux does not flow. Therefore, an area other than the detection area D _B is abraded powder is hardly adsorbed.

Thus, also in this second embodiment, by permanent magnets 402B and the gap G _B is disposed at an appropriate positional relationship, selective limited area within the gap G _B as a detection area D _B Is set to Since wear powder is intensively sucked to the suction amount was stabilized detection area D _B, the output of the sensor 40B is stabilized. Therefore, the host control device can detect (with high reliability) an increase in the amount of wear powder generated.

In the second embodiment, only the whole gap G _B is not limited to the detection area D _B are exposed on the exterior. Since the structure as compared with the embodiment 1 surround takes detection area D _B is small, hardly wear particles are attracted to the detection area D _B is blocked by the structure, easily adsorbed in the detection region D _B.

Note that the shapes and positional relationships of the permanent magnet 402B and the box-like electrodes 404B and 406B are not limited to those illustrated in FIG. If a configuration in which part of the region only abrasion powder is intensively absorbed in the gap G _B, may be replaced with other shapes and positional relationship.

Further, in this embodiment, the sensor 40B is not attracted to the outer surface of the sensor 40F due to the shape, size, arrangement, etc. of the permanent magnet 402B and the box-shaped electrodes 404B and 406B. is constrained to the flux solely within the detection area D _B are integrated. The permanent magnet 402B may be a magnet or an electromagnet. The shape of the box-shaped electrodes 404B and 406B is not limited to the box shape, and may be a circular arc shape formed only in the disk shape or the detection region DB.

[Example 3]
FIG. 5 is a diagram illustrating a configuration of a sensor 40C according to the third embodiment of the present invention. FIG. 5A and FIG. 5B are a plan view and a front view of the sensor 40C, respectively. 5 (c) is a sectional view taken along _A C -A _C line in FIG. 5 (a). FIG. 5D is a sectional view taken along line B _C -B _C in FIG.

  As shown in FIG. 5, the sensor 40C according to the third embodiment is easy to handle as a component of the sensor 40C by attaching resin protective members 410C and 412C to the sensor 40B according to the second embodiment. The structure (insulating property) is improved. In other words, the configuration is such that the operator's touch with the electrode is reduced and electric shock is difficult.

The protection members 410C and 412C cover the entire outer surfaces of the box electrodes 404C and 406C, respectively. However, the detection since the region D not hampered the abrasion powder is attracted to _B, the interval of the end surface between the protective member 410C and the protective member 412C that face is set equal to or larger than the width of at least the gap portion G _B. In other words, the protective member 410C and the protective member 412C, and is opening is formed in a region including at least the whole gap G _B.

Also in the third embodiment, since the abrasion powder is intensively adsorb the detection area D _B where adsorption amount is stabilized, the output of the sensor 40C is stabilized. Therefore, the host control device can detect (with high reliability) an increase in the amount of wear powder generated.

[Example 4]
FIG. 6 is a diagram illustrating a configuration of a sensor 40D according to the fourth embodiment of the present invention. 6A and 6B are a plan view and a front view of the sensor 40D, respectively. 6 (c) is a sectional view taken along _A D -A _D line in FIG. 6 (a). FIG.6 (d) is sectional drawing in the _BD - _BD line | wire of FIG.6 (b).

  As shown in FIG. 6, the sensor 40D includes a permanent magnet 402B, a box electrode 404Ba (first electrode), a box electrode 404Bb (first electrode), a box electrode 406Ba (second electrode), and a box electrode 406Bb. (Second electrode) and a holding member 408B. In this embodiment, two pairs of output lines (signal lines 41a and 41b and signal lines 42a and 42b) are connected to the sensor 40D. As shown in FIG. 6C, the signal lines 41a, 41b, 42a and 42b are connected to the box-shaped electrodes 404Ba, 404Bb, 406Ba and 406Bb, respectively.

  The sensor 40D according to the fourth embodiment divides the box electrode 404B into two electrodes (the box electrode 404Ba and the box electrode 404Bb) and the box electrode 406B with respect to the sensor 40B according to the second embodiment. The structure is divided into two electrodes (box electrode 406Ba and box electrode 406Bb). A gap G ′ is formed between the box electrode 404Ba and the box electrode 404Bb. A gap portion G ″ is formed between the box-shaped electrode 406Ba and the box-shaped electrode 406Bb.

Foreign matter (for example, chips) having a large particle size when machining a mechanical device such as the speed reducer 20 may be mixed in the oil bath 20B. When this type of foreign matter is adsorbed to the gap _GBa , for example, even when almost no abrasion powder is generated, the electrodes are short-circuited at that time, and the output level of the output line changes, generating abrasion powder. There is a risk of erroneous detection that the amount has increased.

Thus, in the fourth embodiment, a gap portion G _Bb is formed in addition to the gap portion G _Ba . In the fourth embodiment, the detection signal can be transmitted by short-circuiting between the electrodes in all the gap portions (gap portions G _Ba and G _Bb ). Or you may control so that a high-order control apparatus may judge that abrasion powder increased. Thereby, the erroneous detection due to disturbance (for example, chips having a large particle diameter) is reduced, and the host controller can reliably (with high reliability) detect an increase in the amount of wear powder generated. Also in the case of digital detection, when a short circuit signal (ON signal) is detected in both the detection region DBa and the detection region DBb, it may be determined that the wear powder has increased.

[Example 5]
FIG. 7 is a diagram illustrating a configuration of a sensor 40E according to the fifth embodiment of the present invention. 7A to 7C are a plan view, a right side view, and a front view of the sensor 40E, respectively. FIG.7 (d) is sectional drawing in the _AE - _AE line of Fig.7 (a). FIG.7 (e) is sectional drawing in the _BE - _BE line of FIG.7 (c).

  The sensor 40E has a configuration in which a mesh cover 412E (filter member) is attached to the sensor 40A according to the first embodiment described above.

Mesh cover 412E covers the entire gap portion _{G A} (and jacket member 410A). Therefore, for example, chips and abrasion powder of the larger particle size than the mesh size is avoided inconvenience adsorbed to the detection region D _A. Therefore, robustness is improved.

In Example 5, the adsorption amount for stable detection area D _A fine abrasion powders are intensively absorbed, the output of the sensor 40E is more stable. Therefore, the host control device can detect (with high reliability) an increase in the amount of wear powder generated.

[Example 6]
FIG. 8 is a diagram illustrating a configuration of a sensor 40F according to Embodiment 6 of the present invention. FIG. 8A is a plan view of the sensor 40F, and FIG. 8B is a front view. FIG. 8C is a cross-sectional view of the cutting plane indicated by the cutting line A _F -A _F in FIG. 8A, and FIG. 8D is a cutting line B in FIG. it is a cross-sectional view of the section indicated by _F -B _F.

  The sensor 40F includes a permanent magnet 402F, a box electrode 406F (second electrode), a lid electrode 404F (first electrode), a holding member 408B, an insulating sheet 407F, a male screw 414F, and a nut 415F. As shown in FIG. 8C, the signal line 41 is connected to the lid electrode 404F, and the signal line 42 is connected to the box electrode 406F.

  The box-like electrode 406F and the lid-like electrode 404F are magnetic members formed of a conductive magnetic material.

  The box-like electrode 406F has a cylindrical side wall part 406Fa and a cylindrical box-like (bottomed cylinder) having a disk-like bottom part 406Fb that closes an opening on one end side (lower side) in the axial direction of the side wall part 406Fa. Member). A through hole 406Fh through which the shaft of the male screw 414F passes is formed concentrically at the center of the bottom portion 406Fb.

The lid electrode 404F is a substantially disk-shaped member, and a through hole 404Fh through which the shaft of the screw 414F passes is formed concentrically at the center thereof. The outer diameter of the lid electrode 404F is smaller than the inner diameter of the side wall portion 406Fa of the box electrode 406F, and there is an external space of the sensor 40F between the outer circumferential surface of the lid electrode 404F and the inner circumferential surface of the box electrode 406F. An annular hollow portion (gap G _F ) connected to (oil bath 20B) is formed.

  The permanent magnet 402F is a substantially disk-shaped member, and a through hole 402Fh through which the shaft of the screw 414F passes is formed concentrically at the center.

  The holding member 408F is a cylindrical member formed from the same resin (nonmagnetic material) as the holding member 408A of the first embodiment. A box electrode 406F is concentrically embedded in the holding member 408F. The outer diameter of the holding member 408F is slightly smaller than the inner diameter of the side wall portion 406Fa of the box-like electrode 406F, and the holding member 408F is concentrically disposed at the bottom of the hollow portion of the box-like electrode 406F. Therefore, the permanent magnet 402F is positioned and held concentrically within the hollow portion of the box-like electrode 406F by the holding member 408F. Further, the height (length in the axial direction) of the holding member 408F is the same as the height of the permanent magnet 402F, and the upper surfaces of the holding member 408F and the permanent magnet 402F are arranged on substantially the same plane.

  The insulating sheet 407F is a thin plate-like member having electrical insulation formed from paper, resin, or the like. The insulating sheet 407F is a circle having an outer diameter larger than that of the permanent magnet 402F, and a through hole 407Fh through which the shaft of the screw 414F passes is formed concentrically at the center. The insulating sheet 407F is laid on the bottom 406Fb of the box electrode 406F to electrically insulate the box electrode 406F from the permanent magnet 402F.

  The male screw 414F and the nut 415F are non-magnetic members each having electrical insulation formed from resin.

  In the sensor 40F, an insulating sheet 407F is laid on the bottom 406Fb of the box electrode 406F, a holding member 408F and a permanent magnet 402F are placed thereon, and a lid electrode 404F is further stacked thereon to Is passed through the through holes 404Fh, 406Fh, 407Fh and 408Fh and fitted into the nut 415F, and the box-like electrode 406F, the insulating sheet 407F, the permanent magnet 402F / holding member 408F and the lid-like electrode 404F are integrated by the male screw 414F and the nut 415F. It is assembled by tightening.

Permanent magnet 402F is being magnetized in the arrow _{M F} direction in FIG. 8 (c), the the sensor 40F, as indicated by arrows phi _F in FIG. 8 (c), the magnetic flux path is formed through a gap _{G F} The In the present embodiment, the radial magnetic flux phi _F is emitted from the entire circumference of the outer circumferential surface of the cap-like electrode 404F radially entire circumference of the annular gap G _F is the detection area D _F.

The total height of the insulating sheet 407F, the permanent magnet 402F, and the lid electrode 404F stacked in the axial direction in the hollow portion of the box electrode 406F is the same as the depth of the hollow portion of the box electrode 406F. Therefore, the upper surface of the lid electrode 404F after assembly and the upper end surface of the box electrode 406F are arranged on the same plane. The shape of the cap-like electrodes 404F and a box-shaped electrode 406F, dimensions, by adjusting the arrangement and the like, the magnetic flux phi _F is, exits vertically from the outer peripheral surface of the lid-shaped electrode 404F, straight through the gap G _F, a box-shaped The electrode 406F is configured to be perpendicular to the inner peripheral surface. Therefore, the magnetic flux phi _F is without hardly leaks to the outside of the magnetic flux path phi _F, the abrasion powder does not adsorb on the outer surface or the like of the sensor 40F, it is constrained to the flux phi _F exclusively the detection area D _F Accumulate. That is, accumulation of wear powder outside the detection area D _F is suppressed and concentrated in the detection area D _F , so that highly sensitive detection is possible. In addition, since the detection region DF is formed in a circumferential shape, a large amount of wear powder can be accumulated, and damage to a crisis such as a reduction gear caused by the wear powder can be reduced.

[Example 7]
FIG. 9 is a diagram illustrating a configuration of a sensor 40G according to the seventh embodiment of the present invention. FIG. 9A is a plan view of the sensor 40G, and FIG. 9B is a front view. FIG. 9C is a cross-sectional view taken along the cutting line A _G -A _G in FIG. 9A, and FIG. 9D is a cutting line B _{G in} FIG. 9B. it is a cross-sectional view of the section indicated by -B _G.

The sensor 40G is obtained by changing a part of the configuration of the sensor 40D of the fourth embodiment (specifically, the box-shaped electrodes 404Bb and 406Bb). In the sensor 40D of the fourth embodiment, the box-shaped electrodes 404Ba and 404Bb have the same length in the Z-axis direction, and the box-shaped electrodes 406Ba and 406Bb have the same length in the Z-axis direction. The gap length G _Ba between 406Ba and the gap portion G _Bb between the box-shaped electrode 404Bb and the box-shaped electrode 406Bb have the same gap length (electrode spacing in the gap portion). In contrast, in this embodiment, the length of the box-shaped electrode 404Bb ′ in the Z-axis direction is longer than that of the box-shaped electrode 404Ba, and the length of the box-shaped electrode 406Bb ′ in the Z-axis direction is longer than that of the box-shaped electrode 406Ba. long since, than gap _{G Ba} between the box-shaped electrodes 404Ba and box-shaped electrodes 406Ba, towards the gap _{G BB 'between} the box-shaped electrodes 404Bb' a box-shaped electrodes 406Bb' is, the gap length is shortened ing.

In the present embodiment, as described above, since the gap portion G _Bb ′ has a shorter gap length than the gap portion G _Ba , the detection region D _Bb ′ is necessary for conduction between the electrodes than the detection region D _Ba. Accumulated wear powder is small and conducts quickly. That is, in this embodiment, the positive electrode and the negative electrode (box-like electrode 404B and box-like electrode 406B) are divided into two to provide two pairs of electrodes, and the gap length between each pair of electrodes is different. By doing so, it is possible to set two thresholds for the amount of iron powder that causes conduction between electrodes (that is, the timing at which conduction occurs). By using a sensor having such a configuration, it is possible to detect an increase in wear powder in stages, so that the progress of wear of the parts of the reducer can be grasped in more detail. It is possible to more accurately predict the failure.

[Example 8]
FIG. 10 is a diagram illustrating a configuration of a sensor 40H according to the eighth embodiment of the present invention. FIG. 10A is a plan view of the sensor 40H, and FIG. 10B is a front view. FIG. 10C is a cross-sectional view taken along the cutting line A _H -A _H in FIG. 10A, and FIG. 10D is a cutting line B _{H in} FIG. it is a cross-sectional view of the section indicated by -B _H.

  The sensor 40H changes a part of the configuration of the sensor 40F of the sixth embodiment (specifically, the lid electrode 404F) and detects an increase in wear powder in a stepwise manner as in the sensor 40G of the seventh embodiment. It is something that can be done.

  The lid electrode 404H of this embodiment includes four electrodes 404Ha, 404Hb, 404Hc, and 404Hd, and four spacers 404Hs. The electrodes 404Ha to d are magnetic members obtained by dividing the disc-shaped lid electrode 404F of Example 6 into four fan shapes. However, the radii of the fans of the electrodes 404Ha, 404Hb, 404Hc, and 404Hd increase stepwise (for example, in an equal manner) in this order. In this embodiment, one signal line 41 (ground line) and four signal lines 42a, 42b, 42c and 42d constitute an output line. As shown in FIG. 10D, the signal line 41 is connected to 406F, and the signal lines 42a, 42b, 42c, and 42d are connected to the electrodes 404Ha, 404Hb, 404Hc, and 404Hd, respectively.

  The spacer 404Hs is a plate-like member formed of a nonmagnetic material having electrical insulation properties such as resin or ceramics. The four electrodes 404Ha to d are bonded in the circumferential direction with an adhesive or the like via the spacer 404Hs.

Since the radius of the cap-like electrodes 404H changes stepwise in the circumferential direction, also the gap length of the gap portion G _F between the outer surface and the inner circumferential surface of the box-shaped electrodes 406F lid-shaped electrodes 404H, It changes stepwise in the circumferential direction. Gap _{G F} is divided electrodes 404Ha, 404Hb, 404Hc and each adjacent gap _G Ha in _404Hd, G _Hb, and _{G Hc} and _{G Hd,} the gap _{G Hs} of four locations adjacent each spacer 404Hs . The gap portions G _Ha , G _Hb , G _Hc and G _{Hd become} detection regions D _Ha , D _Hb , G _Hc and G _Hd , respectively, because the magnetic flux φ _H passes through the gap portions G _Ha , G _Hb , G _Hc and G _Hd . The gap portion G _Hs is a non-detection region because the magnetic flux φ _H that accumulates the wear powder does not pass therethrough.

The gap lengths of the gap portions G _Fa , G _Fb , G _Fc, and G _Fd (detection regions D _Ha , D _Hb , G _Hc, and G _Hd ) are reduced in this order, for example, in an equal manner. The amount of wear powder accumulated for conduction is also decreasing in this order. Therefore, conduction between the electrodes occurs in the reverse order, that is, in the order of the detection regions D _Hd , D _Hc , G _Hb , and G _Hd . In other words, the sensor 40H of the present embodiment can detect the increase in wear powder in four stages, which is higher than the sensor 40G of the seventh embodiment, and therefore the progress of wear of the parts of the reducer can be further detailed. Therefore, it is possible to predict a reduction gear failure more accurately.

  In the present embodiment, a configuration using the electrodes 404Ha to d obtained by dividing the lid-like electrode 404F into four parts is adopted, but it may be divided into two parts, three parts, five parts or more.

  The above is the description of the exemplary embodiments of the present invention. Embodiments of the present invention are not limited to those described above, and various modifications are possible within the scope of the technical idea of the present invention. For example, the embodiment of the present application also includes contents appropriately combined with embodiments or the like clearly shown in the specification or obvious embodiments.

  For example, in the above embodiment, the sensor 40 is provided in a speed reducer that constitutes a swivel body of the industrial robot 1 or a swivel part of an arm joint, but in another embodiment, a swivel part of another machine tool. It may be provided in a reduction gear that constitutes the above.

  Further, the sensor 40 is not limited to the oscillating speed reducer illustrated in FIG. 2 but may be provided in other types of speed reducers such as a planetary gear speed reducer.

  The sensor 40 is not limited to a speed reducer and may be used for other mechanical devices. As an example, the sensor 40 may be diverted to a check sensor for checking the degree of engine oil contamination.

Moreover, according to the first embodiment, although the non-detection area is provided by plugging part of the gap portion G _A jacket member 410A (covering member), a magnetic shield member for shielding a magnetic (e.g., iron or the like The non-detection region can also be provided by covering a part of the gap portion with a resin of a ferromagnetic net of 3) and covering the outer space with a magnetic shield.

DESCRIPTION OF SYMBOLS 1 Industrial robot 20 Reduction gear 30 Servo motor 40A Sensor 202 Input shaft 202a Drive side gear 204 Input gear 206 Case 208 Carrier 210 Crank shaft 212a, 212b Oscillating gear 214 Support member 402A Permanent magnet 406A Box-shaped electrode 408A Holding member 410A Jacket Member A1-A5 Arm J1-J6 Joint part

Claims (16)

A sensor that applies a magnetic field between the electrodes, accumulates magnetic powder floating in the lubricating oil between the electrodes, and detects a decrease in electrical resistance between the electrodes,
A detection region capable of accumulating the magnetic powder is provided in at least a part between the electrodes,
Accumulation of the magnetic powder is suppressed in a non-detection region that is a space around the electrode other than the detection region,
A sensor characterized by that. The electrode is
A first electrode;
A second electrode,
A gap is provided between the first electrode and the second electrode;
A detection region to which the magnetic field is applied is provided in at least a part of the gap portion.
The sensor according to claim 1. The first electrode is a magnet for generating the magnetic field;
The sensor according to claim 2. A magnet for generating the magnetic field;
The sensor according to claim 2. In the non-detection region, provided with a covering member that covers the electrode and suppresses the accumulation of the magnetic powder,
The sensor according to any one of claims 3 to 4. The entire circumference of the magnet was covered with a magnet covering member,
The sensor according to any one of claims 3 to 5. The magnetic field is selectively applied to the sensing region;
The sensor according to any one of claims 3 to 6. A plurality of the detection areas are provided,
The sensor according to any one of claims 3 to 7. Having a first detection area and a second detection area;
The first sensing region is provided adjacent to the north pole of the magnet;
The second detection region is provided adjacent to the south pole of the magnet.
The sensor according to claim 8. A plurality of the second electrodes;
The gap portions are provided between the plurality of second electrodes and the first electrode, respectively.
The detection region is provided in each of the gap portions,
The sensor according to claim 8. In the plurality of detection regions, the gap lengths are different from each other.
The sensor according to claim 10. A plurality of electrode pairs of the first electrode and the second electrode;
In the plurality of electrode pairs, the gap lengths are different from each other.
The sensor according to claim 8. Has a narrow recess on the outer periphery,
The detection area is provided at the back of the recess,
The sensor according to any one of claims 3 to 12. A filter member that is disposed between the detection region and the external space and prevents the passage of foreign particles having a large particle diameter,
The sensor according to any one of claims 3 to 13. Constructed so that magnetic flux does not leak outside from the detection area,
The sensor according to any one of claims 3 to 14. The detection area is
A first plane formed on the first electrode;
A region sandwiched between a second plane formed in the second electrode and facing in parallel with the first plane;
The magnetic flux intersects the first plane and the second plane perpendicularly in the detection region;
The sensor according to any one of claims 3 to 15.

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