JP2007205830A - Lubricant degradation detector, and bearing with detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant degradation detector that does not fix an interval between a light source and a light reception detecting element, increases the degree of freedom of layout, and stably estimates the degradation state of a lubricant without being affected by the thickness of the lubricant as a measured object, and also to provide a bearing with a detector having the lubricant degradation detector. <P>SOLUTION: The lubricant degradation detector 1 comprises: the light source 2; two light detecting elements 3 and 4 for detecting transmitted light that comes from the light source 2 and transmits through the lubricant 6; and a determining means 5. The positions of light detection surfaces of the two light detecting elements 3 and 4 are mutually shifted from the light travelling direction. The determining means 5 detects the degradation state of the lubricant 6 by comparing the signal intensities of the outputs of the two light detecting elements 3 and 4 with each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lubricant deterioration detection device for detecting a deterioration state due to a contaminant of a lubricant, and a bearing with a detection device provided with the lubricant deterioration detection device, for example, for railway vehicles, automobiles, industrial machinery, etc. The present invention relates to a bearing with a lubricant deterioration detection device.

  In a bearing in which a lubricant is enclosed, if the lubricant (grease, oil, etc.) inside the bearing deteriorates, the rolling element will be poorly lubricated and the bearing life will be shortened. Judging the poor lubrication of the rolling elements from the vibration state of the bearing, etc., will be dealt with after an operational abnormality occurs due to the end of the life, so the abnormality of the lubricating state cannot be detected earlier. Therefore, it is desired to observe the state of the lubricant in the bearing periodically or in real time so that the abnormality or the maintenance period can be predicted.

As a major factor in the deterioration of the lubricant, wear powder generated with use of the bearing is mixed into the lubricant.
A sensor-equipped bearing in which a sensor such as an electrode or a coil is arranged inside the seal of the bearing so that the electrical characteristics of the lubricant mixed with wear powder can be detected by the sensor. Has been proposed (for example, Patent Document 1).
JP 2004-293776 A

  However, the sensor-equipped bearing of Patent Document 1 is for detecting the electrical characteristics of the lubricant. Therefore, unless a situation occurs such that a large amount of wear powder enters and conduction occurs, it is not detected as a characteristic change. Detection of contaminants may be difficult.

  In order to solve such a problem, for example, as shown in FIG. 8, a lubricant 35 is interposed between the light emitting element 33 and the light receiving element 34 arranged so as to face each other, and light emitted from the light emitting element 33 and transmitted through the lubricant 35. An optical configuration is considered in which the deterioration state of the lubricant 35 is estimated from the amount of light detected by the light receiving element 34.

  However, in the case of this configuration, when the thickness d of the lubricant 35 to be detected changes as indicated by a broken line in the figure, the amount of light detected by the light receiving element 34 changes. It is necessary to have a configuration that keeps constant.

Therefore, for example, as shown in FIG. 9, one end of each of the optical fibers 36 and 37 on the light emitting side and the light receiving side is opposed to the measuring unit 38 in which the lubricant 35 to be detected exists, and the other end of the optical fiber 36 on the light emitting side. A configuration in which the light emitting element 33 and the light receiving element 34 are arranged on the other end of the light receiving side optical fiber 37 is considered.
In the configuration of FIG. 9, the light emitted from the light emitting element 33 passes through the lubricant 35 present in the measuring unit 38 via the light emitting side optical fiber 36, and further receives light via the light receiving side optical fiber 37. The amount of foreign matter mixed in the lubricant 35 is estimated from the amount of transmitted light detected by the element 34 and detected by the light receiving element 34. In this case, since the area facing the optical fibers 36 and 37 in the measurement unit 38 can be reduced, the lubricant 35 can easily enter the measurement unit 38, and the lubricant 35 entering the measurement unit 38 is easily maintained at a constant thickness. be able to.

  However, even in the case of the configuration of FIG. 9, a measuring unit 38 having a container structure in which the lubricant 35 is maintained at a constant thickness d is necessary, and for example, it is used for detecting deterioration of the lubricant enclosed in the bearing. In this case, the degree of freedom of arrangement inside the bearing is reduced.

The object of the present invention is to stabilize the deterioration state of the lubricant without being affected by the thickness of the lubricant that is the object to be measured, while the interval between the light source and the light receiving detection element is not fixed and the degree of freedom of arrangement is increased. It is an object of the present invention to provide a lubricant deterioration detection device that can be estimated as described above.
Another object of the present invention is to provide a high degree of freedom in the arrangement of the lubricant deterioration detection device of the present invention inside the bearing, and to stably estimate the deterioration state of the lubricant without being affected by the thickness of the lubricant. It is another object of the present invention to provide a bearing with a detection device that can easily detect deterioration of a lubricant on a regular or real-time basis.

  The lubricant deterioration detection device of the present invention includes a light source and two light detection elements that detect transmitted light emitted from the light source and transmitted through the lubricant, and the two light detection elements are provided on the light detection surface. It is assumed that the positions are deviated from each other with respect to the light traveling direction, and determination means for detecting the deterioration state of the lubricant by comparing the signal intensities of the outputs of the two light detection elements is provided.

According to the lubricant deterioration detection device of this configuration, the light from the light source is attenuated by absorption or scattering before reaching the light detection element, but the intensity of this light is detected by the first light detection element. . When the output of the second photodetecting element is evaluated with reference to the output of the first photodetecting element that the light reaches first, the attenuation of the light due to the distance between the two photodetecting elements can be detected. . As described above, since the light attenuation due to the distance between the two light detection elements is detected, if the distance between the light detection elements is fixed, measurement independent of the intensity of the light source and the distance from the light source can be performed. it can. Therefore, by using this output difference, it is possible to estimate the state of deterioration of the lubricant, for example, the amount of contaminants generated due to wear, without being affected by the thickness of the lubricant.
Since it is not necessary to fix the distance between the light source and the light detection element, the degree of freedom in arrangement is increased, and a configuration that matches the restrictions on the mounting space is possible. In addition, since the detection is performed by comparing the signal intensities of the two photodetecting elements, stable detection is possible without being affected by common mode noise such as power fluctuation. Even if the two photodetecting elements are arranged in the lubricant, the influence of the characteristic change due to the temperature change is canceled between the two photodetecting elements, and detection with high accuracy is possible.

In the present invention, the determination means may estimate the amount of contaminants mixed in the lubricant by comparing the signal intensities.
For example, when the lubricant is sealed in the bearing, foreign matter such as wear powder is mixed into the lubricant as the bearing is used. The detection output becomes small. Therefore, it is possible to estimate the amount of the contaminant mixed in the lubricant from the value of the detection output of the determination means. Further, since the increase in the amount of contamination means the progress of the deterioration state of the lubricant, the determination unit can detect the deterioration state of the lubricant from the estimated amount of contamination.

  In the present invention, the light detection element may be composed of a detector and a light guide body whose base end is connected to the detector and whose front end is the light detection surface. Even in this configuration, the two photodetecting elements are arranged such that the positions of their photodetecting surfaces are deviated from each other by a predetermined interval with respect to the light traveling direction. The deterioration state of the lubricant can be detected without being affected by the intensity of the light source, the distance from the light source to the light detection element, and the like.

  In the present invention, the photodetecting element may comprise a detector and an optical fiber having a base end connected to the detector and having a tip serving as the photodetecting surface. Even in this configuration, the two photodetecting elements are arranged such that the positions of their photodetecting surfaces are deviated from each other by a predetermined interval with respect to the light traveling direction. The deterioration state of the lubricant can be detected without being affected by the intensity of the light source, the distance from the light source to the light detection element, and the like.

  In the present invention, a temperature sensor may be disposed in the vicinity of the light detection element. In the case of this configuration, by observing the temperature of the lubricant and the light detection element with the temperature sensor, it is possible to correct the detection result according to the temperature change. Thereby, more accurate detection is possible, and it is possible to avoid mistaking the change in the detection signal due to the change in the environmental temperature as being caused by the deterioration of the lubricant.

The bearing with the lubricant deterioration detecting device of the present invention is equipped with the lubricant deterioration detecting device of the above invention.
According to this configuration, it is possible to easily detect the deterioration of the lubricant sealed in the bearings regularly or in real time. As a result, it is possible to determine the necessity of replacement of the lubricant before the operation abnormality occurs in the bearing, and it is possible to prevent the bearing from being damaged due to poor lubrication. Further, since the necessity of replacing the lubricant can be determined by the output of the lubricant deterioration diameter device, the amount of lubricant discarded before the expiration date is reduced.

The lubricant deterioration detection device of the present invention includes a light source and two light detection elements that detect transmitted light that has been emitted from the light source and transmitted through the lubricant, and the two light detection elements are provided on a light detection surface. Since the position is deviated from the traveling direction of the light, and there is provided determination means for detecting the deterioration state of the lubricant by comparing the signal intensities of the outputs of the two light detecting elements, the light source and the light receiving detecting element are provided. Thus, the deterioration state of the lubricant can be stably estimated without being affected by the thickness of the lubricant as the object to be measured, while increasing the degree of freedom of arrangement.
Since the bearing with the lubricant deterioration detecting device of the present invention is equipped with the lubricant deterioration detecting device of the present invention, the deterioration of the lubricant enclosed in the bearing is accurately detected periodically or in real time. Can be done easily. As a result, it is possible to determine the necessity of replacement of the lubricant before the operation abnormality occurs in the bearing, and it is possible to prevent the bearing from being damaged due to poor lubrication. In addition, since the necessity for replacing the lubricant can be determined by the output of the lubricant deterioration detecting device, the amount of lubricant discarded before the expiration date is reduced.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a lubricant deterioration detection device according to this embodiment. The lubricant deterioration detection device 1 includes a light source 2, two light detection elements 3 and 4 that detect light transmitted from the light source 2 and transmitted through the lubricant 6 to be detected, and the two light detections. And determining means 5 for detecting the deterioration state of the lubricant 6 by comparing the signal strengths of the outputs of the elements 3 and 4. The lubricant 6 to be detected is, for example, a lubricant sealed inside the bearing. The two photodetecting elements 3 and 4 are arranged such that the positions of the photodetecting surfaces are shifted from each other by a predetermined distance d with respect to the light traveling direction, and are treated as an integral part connected in such a shifted state. . The two light detection elements 3 and 4 are disposed in the lubricant 6. As a result, the difference in lubricant thickness from the light incident surface of the lubricant 6 to the light detection surfaces of the light detection elements 3 and 4 is d.

  As the light source 2, an LED, an incandescent bulb, a semiconductor laser diode, an EL, an organic EL, a fluorescent tube, or the like can be used. Further, as the light detection elements 3 and 4, a detector such as a photodiode, a phototransistor, a CDS, a solar cell, or a photomultiplier tube can be used. Although FIG. 1 shows an example in which the determination unit 5 is configured by a differential amplifier circuit that obtains a difference in signal intensity between the outputs of the two photodetecting elements 3 and 4, the present invention is not limited to this. A circuit configuration for obtaining the ratio of the signal strengths of the outputs of the detection elements 3 and 4 may be employed.

In the lubricant deterioration detecting device 1 having the above-described configuration, the intensity of light transmitted through the lubricant 6 is greatly attenuated depending on the transmitted distance. The relationship shown by the graph in FIG. 2 is present between the transmitted light intensity and the transmission distance. Assuming that the transmitted light intensity (transmitted light amount) is I, the transmission distance is x, and the incident light amount to the lubricant 6 is Iin, α is a constant,
I = Iinexp (−αx) (1)
It becomes.
Therefore, the signal intensities I0 and I1 at the outputs of the light detection elements 3 and 4 are
I0 = Iinexp (-αx0) (2)
I1 = Iinexp (-αx1) (3)
It becomes. Assuming that the determination means 5 determines the ratio of the signal strengths of the outputs of the two light detection elements 3 and 4, the detection output of the determination means 5 is
(I1 / I0) = exp (-[alpha] (x1-x0))
= Exp (-αd) (4)
It becomes. That is, the detection output of the determination unit 5 is a value that depends on the distance d between the light detection surfaces of the two light detection elements 3 and 4 regardless of the thickness of the lubricant 6 itself.

  Further, the value of the constant α in the formula (4) varies depending on the state of the lubricant 6. For example, when the lubricant 6 is sealed in the bearing, foreign matter such as wear powder is mixed into the lubricant 6 as the bearing is used, so that the amount of the contaminant increases as the amount of the contaminant increases. The constant α increases. Therefore, when the determination means 5 obtains the ratio of the signal intensity of the two light detection elements 3 and 4 as described above, the transmittance of the light transmitted through the interval d in the lubricant 6 is detected. The amount of contaminants mixed in the lubricant 6 can be estimated from the value of the detected output. Further, since the increase in the amount of contamination means the progress of the deterioration state of the lubricant 6, the determination means 5 can detect the deterioration state of the lubricant 6 from the estimated amount of contamination.

  The determination means 5 may obtain a difference in signal intensity between the two light detection elements 3 and 4. Also in this case, the determination means 5 detects the transmittance of light transmitted through the interval d in the lubricant 6, and therefore estimates the amount of contaminants mixed in the lubricant 6 from the detected output. The deterioration state of the lubricant 6 can be detected from the estimated amount of contaminants.

  Thus, in this lubricant deterioration detection device 1, the two light detection elements 3 and 4 are arranged so that the positions of their light detection surfaces are shifted from each other by the distance d with respect to the light traveling direction. Since the determination means 5 compares the output signal intensity of the two light detection elements 3 and 4 to detect the deterioration state of the lubricant 6, the thickness of the lubricant 6 itself, the intensity of the light source 2, the light source The deterioration state of the lubricant 6 can be detected without being affected by the distance from 2 to the light detection elements 3 and 4.

  As a result, even when the lubricant deterioration detection device 1 is installed inside the bearing or the like, the degree of freedom of arrangement becomes high, and a configuration that matches the restrictions on the installation space becomes possible. Further, since the deterioration state of the lubricant 6 is detected by comparing the signal intensities of the outputs of the two light detecting elements 3 and 4, stable detection is possible without being affected by common mode noise such as power supply fluctuation. Become. In addition, since the two photodetecting elements 3 and 4 are arranged in the lubricant 6, the influence of the characteristic change due to the temperature change is canceled between the two photodetecting elements 3 and 4, and detection with high accuracy is possible. Become.

  In the above configuration, a temperature sensor is arranged in the vicinity of the arrangement portion of the two light detection elements 3 and 4, and the temperature of the lubricant 6 and the light detection elements 3 and 4 is observed, so that correction according to the temperature change is performed. May be applied to the detection result. Specifically, for example, a change in the detection signal due to a temperature change may be measured in advance, and a circuit for correcting the detection signal at the actual use temperature may be provided separately. In this case, if the temperature of the lubricant 6 is known, it is possible to avoid mistaking the change of the detection signal due to the change of the environmental temperature as being caused by the deterioration of the lubricant 6. Thereby, more accurate detection becomes possible.

  In the above configuration, the determination unit 5 may include a comparison circuit that compares a detection signal obtained by comparing the signal strengths of the outputs of the two light detection elements 3 and 4 with a predetermined reference value. In this case, since it can be easily determined that the deterioration state of the lubricant 6 is at a predetermined level or more, it can be used as a guideline for the replacement time of the lubricant 6.

  FIG. 3 shows a schematic configuration diagram of another embodiment of the present invention. The lubricant deterioration detection device 1 according to this embodiment includes two photodetectors 3 and 4 including detectors 13A and 14A and light guides 13B and 14B in the first embodiment shown in FIG. Is. That is, one photodetecting element 3 is composed of a detector 13A and a light guide 13B whose base end is connected to the detector 13A and the tip is a photodetecting surface, and the other photodetecting element 4 is The detector 14A and another light guide 14B having a proximal end connected to the detector 14A and having a distal end serving as a light detection surface. As each detector 13A, 14A, a photodiode, a phototransistor, a CDS, a solar cell, a photomultiplier tube, or the like is used. In this case, the two detectors 13A and 14A are arranged side by side at the same position with respect to the light traveling direction. On the other hand, the lengths of the two light guides 13B and 14B are different from each other so that the positions of the tips are shifted from each other by a predetermined distance d with respect to the light traveling direction. Thus, the positions of the light detection surfaces of the two light detection elements 3 and 4 are shifted from each other by a predetermined distance d with respect to the light traveling direction. Each of the light guides 13B and 14B is made of, for example, a cylindrical transparent body, a reflective material is applied to the outer peripheral surface, and a tip serving as a light detection surface is a transparent circular window. In addition, the shape of the light guides 13B and 14B is not limited to a cylindrical shape, and may be, for example, a rectangular tube shape. Other configurations are the same as those in the first embodiment.

  Also in the case of the lubricant deterioration detection device 1 configured as described above, the two light detection elements 3 and 4 are arranged so that the positions of their light detection surfaces are shifted from each other by a distance d with respect to the light traveling direction. Therefore, the deterioration state of the lubricant 6 can be detected without being affected by the thickness of the lubricant 6 itself, the intensity of the light source 2, the distance from the light source 2 to the light detection elements 3 and 4, and the like. .

  FIG. 4 shows a schematic configuration diagram of another embodiment of the present invention. The lubricant deterioration detection device 1 of this embodiment is configured by two detectors 3 and 4 including detectors 13A and 14A and optical fibers 13C and 14C in the first embodiment shown in FIG. It is. That is, one of the light detection elements 3 is composed of a detector 13A and an optical fiber 13C whose base end is connected to the detector 13A and whose tip is a light detection surface, and the other light detection element 4 is a detection element. 14A and another optical fiber 14C whose base end is connected to the detector 14A and whose tip is a light detection surface. As each of the detectors 13A and 14A, a photodiode, a phototransistor, a CDS, a solar cell, a photomultiplier tube, and the like are used as in the embodiment of FIG. Also in this case, the two detectors 13A and 14A are arranged at the same position with respect to the light traveling direction, and the two optical fibers 13C and 14C have their tips positioned at a predetermined interval with respect to the light traveling direction. The lengths are different so as to be shifted by d. Thus, the positions of the light detection surfaces of the two light detection elements 3 and 4 are shifted from each other by a predetermined distance d with respect to the light traveling direction. Other configurations are the same as those in the first embodiment.

  Also in the case of the lubricant deterioration detection device 1 configured as described above, the two light detection elements 3 and 4 are arranged so that the positions of their light detection surfaces are shifted from each other by a distance d with respect to the light traveling direction. Therefore, the deterioration state of the lubricant 6 can be detected without being affected by the thickness of the lubricant 6 itself, the intensity of the light source 2, the distance from the light source 2 to the light detection elements 3 and 4, and the like. .

FIG. 5 is a cross-sectional view in which a bearing with a lubricant deterioration detection device on which the above-described lubricant deterioration detection device 1 is mounted is used in a railway vehicle bearing unit. The railcar bearing unit in this case includes a bearing 21 with a lubricant deterioration detecting device and an oil drainer 22 and a rear lid 23 which are accessory parts provided in contact with both sides of the inner ring 24 respectively. The bearing 21 is a roller bearing, more specifically, a double row tapered roller bearing. The split type inner rings 24 and 24 provided for the rollers 26 and 26 in each row, the integral type outer ring 25, the rollers 26 and 26, respectively. 26 and a retainer 27.
The rear lid 23 is attached to the axle 30 on the center side with respect to the bearing 21 and is in sliding contact with the outer peripheral oil seal 28. The oil drain 22 is attached to the axle 30 and has an oil seal 29 in sliding contact with the outer periphery. A lubricant is sealed inside the bearing 21 by the oil seals 28 and 29 disposed at both ends of the bearing 21, and dust and water resistance are ensured.

The lubricant deterioration detection device 1 is mounted between the raceway surfaces of both rows on the inner diameter surface of the outer ring 25 of the bearing 21 and detects deterioration of the lubricant sealed in the bearing. The lubricant deterioration detection device 1 is disposed near the end face of the roller 26. The outer ring 25 is provided with a cable insertion hole 25a through which the wiring cable 15 of the lubricant deterioration detection device 1 is inserted, and the insertion portion of the wiring cable 15 is subjected to waterproof / oilproof treatment. Through the wiring cable 15, power is supplied from outside the bearing to the lubricant deterioration detecting device 1 and detection signals are taken out from the bearing. This prevents moisture, dust and the like from entering the bearing from the mounting portion of the lubricant deterioration detection device 1.
In this bearing 21 with the lubricant deterioration detecting device equipped with the lubricant deterioration detecting device 1, the deterioration of the lubricant sealed in the bearing can be accurately detected in real time. As a result, it is possible to determine the necessity for replacement of the lubricant before the operation abnormality occurs in the bearing 21, and to prevent damage to the bearing 21 due to poor lubrication. Further, since the necessity of replacing the lubricant can be determined by the output of the lubricant deterioration detecting device 1, the amount of lubricant discarded before the expiration date is reduced.

  FIG. 6 shows another example of a bearing with a lubricant deterioration detection device. This bearing 21A with a lubricant deterioration detecting device is the same as the bearing 21 with a lubricant deterioration detecting device 21 shown in FIG. In this case, the lubricant deterioration detection device 1 is disposed near the end face of the cage 27.

  FIG. 7 shows still another example of the bearing with the lubricant deterioration detecting device. This bearing 21B with a lubricant deterioration detecting device is the same as the bearing 21 with a lubricant deterioration detecting device shown in FIG. 5 except that the lubricant deterioration detecting device 1 described above is attached to the side of the rolling surface of the outer ring 25. is there. As described above, by disposing the lubricant deterioration detection device 1 on the side of the rolling surface, it is possible to reliably detect the state of the lubricant that contributes to lubrication.

1 is a schematic configuration diagram of a lubricant deterioration detection device according to a first embodiment of the present invention. It is a graph which shows the relationship between the transmission distance of the light which permeate | transmits a lubricant, and the intensity | strength of transmitted light. It is a schematic block diagram of the lubricant deterioration detection apparatus which concerns on other embodiment of this invention. It is a schematic block diagram of the lubricant deterioration detection apparatus which concerns on other embodiment of this invention. It is sectional drawing of an example of the bearing with a lubricant deterioration detection apparatus carrying the said lubricant deterioration detection apparatus. It is sectional drawing of the other example of the bearing with a lubricant deterioration detection apparatus carrying the said lubricant deterioration detection apparatus. It is sectional drawing of the further another example of the bearing with a lubricant deterioration detection apparatus carrying the said lubricant deterioration detection apparatus. It is a schematic block diagram of the proposal example of a lubricant deterioration detection apparatus. It is a schematic block diagram of the other proposal example of a lubricant deterioration detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lubricant deterioration detection apparatus 2 ... Light source 3, 4 ... Photodetection element 5 ... Determination means 6 ... Lubricant 13A, 14A ... Detector 13B, 14B ... Light guide 13C, 14C ... Optical fiber 21, 21A, 21B ... Bearing with lubricant deterioration detection device

Claims (6)

  A light source and two light detection elements that detect the transmitted light that has been emitted from the light source and transmitted through the lubricant. The two light detection elements have a light detection surface whose position is relative to the light traveling direction. A lubricant deterioration detection device provided with a determination means for detecting a deterioration state of the lubricant by comparing the signal intensities of the outputs of the two light detection elements.   2. The lubricant deterioration detection apparatus according to claim 1, wherein the determination unit estimates the amount of contaminants mixed in the lubricant by comparing the signal intensities.   3. The lubricant deterioration detecting device according to claim 1, wherein the photodetecting element includes a detector and a light guide body having a base end connected to the detector and having a tip serving as the photodetecting surface. .   3. The lubricant deterioration detecting device according to claim 1, wherein the photodetecting element includes a detector and an optical fiber having a base end connected to the detector and having a tip serving as the photodetecting surface.   The lubricant deterioration detection device according to any one of claims 1 to 4, wherein a temperature sensor is disposed in the vicinity of the light detection element.   A bearing with a detection device, wherein the lubricant deterioration detection device according to any one of claims 1 to 5 is mounted on the bearing.

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