JP2021134839A - Lubricant deterioration state detection device and lubricant deterioration state detection method - Google Patents

Abstract

To improve detection sensitivity and gas selectivity in a device which detects a deterioration state of a lubricant in a rolling bearing.SOLUTION: A lubricant deterioration state detection device includes: a housing 12 which houses a rotatable rolling bearing 15; a semiconductor type gas sensor 13 which is disposed outside the housing 12 and detects a concentration of an object gas; and a guide passage 14 which communicates with the housing 12 and guides a gas in the housing 12 to the semiconductor type gas sensor 13. The lubricant deterioration state detection device detects a deterioration state of a lubricant of the rolling bearing 15 according to a detection result of the semiconductor type gas sensor 13.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lubricant deterioration state detecting device and a lubricant deterioration state detecting method.

Rolling bearings are lubricated with a lubricant such as lubricating oil or grease, and when the lubricant deteriorates, the temperature of the rolling bearings rises and wear occurs, which causes abnormalities such as seizure of the rolling bearings. Since a carbonyl compound is generated as the lubricant deteriorates, it is known that the deteriorated state of the lubricant can be detected by measuring this carbonyl compound. For example, Patent Document 1 proposes to detect a deteriorated state of a lubricant by sucking a gas generated inside a housing containing a rolling bearing and analyzing the sucked gas with a constant potential electrolytic gas sensor. There is.

Japanese Patent No. 6421893

With the constant potential electrolysis type gas sensor, there is a possibility that the detection sensitivity is not sufficient, and the deterioration state cannot be detected with some lubricants due to the gas selectivity, so there is room for improvement. ..
An object of the present invention is to improve detection sensitivity and gas selectivity in detecting a deteriorated state of a lubricant in a rolling bearing.

The lubricant deterioration state detection device according to one aspect of the present invention includes a semiconductor gas sensor.
The lubricant deterioration state detection device according to another aspect of the present invention includes a housing containing a rotatable rolling bearing, a semiconductor gas sensor arranged outside the housing and detecting the concentration of the target gas, and the inside of the housing. It is provided with a guide flow path for guiding the gas in the housing to the semiconductor gas sensor, and detects the deteriorated state of the lubricant of the rolling bearing according to the detection result of the semiconductor gas sensor.
The lubricant deterioration state detection method according to another aspect of the present invention detects the deterioration state of the lubricant by detecting the target gas generated by the deterioration of the lubricant lubricating the rolling bearing with a semiconductor gas sensor. ..

According to the present invention, by detecting the target gas generated from the lubricant of the rolling bearing by the semiconductor gas sensor, it is possible to improve the detection sensitivity and the gas selectivity when detecting the deteriorated state of the lubricant.

It is a figure which shows the lubricant deterioration state detection device. It is a drive circuit of a semiconductor gas sensor. It is a figure which shows the switching of a flow path. It is a graph which shows the test result of an Example. It is a graph which shows the test result of the comparative example. It is a figure which shows the modification.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that each drawing is a schematic one and may differ from the actual one. In addition, the following embodiments exemplify devices and methods for embodying the technical idea of the present invention, and the configuration is not limited to the following. That is, the technical idea of the present invention can be modified in various ways within the technical scope described in the claims.

<< Embodiment >>
"composition"
FIG. 1 is a diagram showing a lubricant deterioration state detecting device.
The lubricant deterioration state detection device 11 includes a housing 12, a semiconductor gas sensor 13, and a guide flow path 14.
The housing 12 houses a rotatable rolling bearing 15. The rolling bearing 15 may be of any kind such as a ball bearing, a roller bearing, a needle bearing, a tapered roller bearing, a spherical roller bearing, and a thrust bearing. The rolling bearing 15 is lubricated by a lubricant, and for example, general-purpose grease is used as the lubricant.
The semiconductor type gas sensor 13 is arranged outside the housing 12 and detects the concentration of the target gas. The target gas contains at least one of alcohol, ketone, aldehyde, and organic acid generated as a result of deterioration of the lubricant.

The guide flow path 14 communicates with the inside of the housing 12 and guides the gas in the housing 12 to the semiconductor gas sensor 13. Specifically, one side is connected to the housing 12, the other side is connected to the suction port of the pump 16, and a semiconductor gas sensor 13 is provided between the housing 12 and the pump 16. A filter 17 is provided between the housing 12 and the semiconductor gas sensor 13 in the guide flow path 14. The filter 17 is, for example, a ceramics filter that removes oil mist and the like contained in the gas. As the filter 17, it is preferable to use a filter having a coarseness of about 200 mesh and capable of collecting oil mist particles having a particle size of 0.3 μm or more.

Of the guide flow paths 14, a branch point is provided between the filter 17 and the semiconductor gas sensor 13, and the branch flow path 21 branched from the branch point is open to the outside of the housing 12. A valve 22 (first flow path switching portion, flow path switching portion) is provided at the branch point. The valve 22 is a three-way valve that switches the gas guided to the semiconductor gas sensor 13 to either the gas inside the housing 12 or the gas outside the housing 12. A filter 23 is provided in the branch flow path 21. The filter 23 is, for example, an activated carbon filter that removes contamination such as dust and dirt.

FIG. 2 is a drive circuit of a semiconductor gas sensor.
The semiconductor gas sensor 13 includes a heater resistance 31 and a sensor resistance 32 which is a metal oxide semiconductor such as stannic oxide SnO2. The heater resistor 31 heats the metal oxide semiconductor to an operating temperature of about 200 to 500 ° C. by applying the heater voltage Eh. A load resistor 33 is connected in series to the sensor resistor 32, and a circuit voltage Ec is applied to the sensor resistor 32 and the load resistor 33 in order to measure the voltage Eout across the load resistor 33. Since the conductivity of the sensor resistor 32 changes according to the concentration of the target gas, the concentration of the target gas can be detected by obtaining the resistance of the sensor resistor 32. Specifically, as shown in the following equation, the resistance value RS of the sensor resistance 32 is calculated according to the circuit voltage Ec, the voltage across the load resistance 33 Eout, and the resistance value RL of the load resistance 33.
RS = {(Ec × RL) / Eout} -RL

Next, a method of detecting the deteriorated state of the lubricant will be described.
FIG. 3 is a diagram showing switching of the flow path.
(A) in the figure shows a state at the time of sensor cleaning. Before detecting the deteriorated state of the lubricant, the semiconductor gas sensor 13 is cleaned. First, the valve 22 switches to a state of communication with the outside of the housing 12 to drive the pump 16. As a result, the gas outside the housing 12 is guided to the semiconductor gas sensor 13 via the branch flow path 21, and the surfaces of the guide flow path 14 around the semiconductor gas sensor 13 and the sensor resistor 32 in the semiconductor gas sensor 13 are cleaned. Will be done. Since it is necessary to replace all the gas in the guide flow path 14 with the gas outside the housing 12, the cleaning time Tc is a value obtained by dividing the flow path volume Vt of the guide flow path 14 by the flow rate Qp per unit time in the pump 16. = Vt / Qp) or higher. For example, if the flow path volume Vt is 200 ml and the flow rate Qp is 100 ml / min, the time Tc is 2 minutes or more, and in order to perform more sufficient cleaning, for example, it is about 19 minutes, which is 9.5 times. Set.

(B) in the figure shows a state at the time of gas measurement. After cleaning the sensor, perform gas measurement. First, the valve 22 switches to a state of communication with the inside of the housing 12 to drive the pump 16. As a result, the gas in the housing 12 is guided by the guide flow path 14 to the semiconductor gas sensor 13, adheres to the surface of the sensor resistor 32, and the concentration of the target gas is detected. For the gas measurement time Ts, it is necessary to replace the gas in the guide flow path 14 with the gas in the housing 12. Therefore, the smaller of the flow path volume Vt of the guide flow path 14 and the volume Vh at which gas can enter in the housing 12 is divided by the flow rate Qp per unit time in the pump 16 (= min [Vt, Vh). ] / Qp) or higher. For example, if the flow path volume Vt is 200 ml, the volume Vh in the housing 12 is 100 ml, and the flow rate Qp is 100 ml / min, the gas measurement time Ts is 1 minute or more.
The above cleaning and gas measurement are set as one set, and this is performed every Ti for a predetermined time. The time Ti is, for example, about several tens of minutes to one day, but it is desirable that the time Ti is within 24 hours because an abnormality occurs in a relatively early time when the lubricant deteriorates.

《Effect》
Next, the main action and effect of the embodiment will be described.
The constant potential electrolysis type gas sensor measures the concentration of the target gas by electrolyzing the target gas at a specific potential and detecting the electrolytic current generated at that time. With this constant potential electrolysis type gas sensor, there is a possibility that the detection sensitivity is not sufficient, and the deterioration state cannot be detected with some lubricants due to the selectivity of the gas, so there is room for improvement. rice field. Therefore, in the lubricant deterioration state detecting device 11 of the present embodiment, the target gas generated by the deterioration of the lubricant lubricating the rolling bearing 15 is detected by the semiconductor gas sensor 13. The semiconductor type gas sensor 13 has the following advantages as compared with the constant potential electrolysis type.

First, since the semiconductor gas sensor 13 is heated to about 200 to 500 ° C. by the heater resistor 31, even if water is present, it is immediately vaporized and is not affected by the water. Similarly, even if the oil is present, it is immediately vaporized and discharged from the guide flow path 14, so that the oil can be prevented from adhering to or accumulating on the sensor resistor 32, and the life can be extended. On the other hand, since the constant potential electrolytic gas sensor does not have a heater, it may be affected by moisture, the detection accuracy may be lowered due to the adhesion or accumulation of oil, or the oil may be erroneously detected as the target gas. ..

Further, since the target gas type of the semiconductor gas sensor 13 covers all carbonyl compounds including alcohols, ketones, aldehydes, and organic acids, it is suitable for detecting the deterioration of the lubricant, and the detection sensitivity is also high. Are better. On the other hand, the constant potential electrolytic gas sensor could not detect alcohol, ketone, organic acid and the like with high accuracy.
Further, since the semiconductor gas sensor 13 has high heat resistance, it can be used in a high temperature environment. On the other hand, the constant potential electrolytic gas sensor does not have high heat resistance, so that the temperature environment in which it can be used is limited.
Therefore, by detecting the target gas generated from the lubricant of the rolling bearing 15 by the semiconductor gas sensor 13, it is possible to improve the detection sensitivity and the gas selectivity when detecting the deteriorated state of the lubricant.

In the lubricant deterioration state detecting device 11, a filter 17 for removing oil mist is provided in the guide flow path 14. As a result, after the oil mist is removed by the filter 17, the gas in the housing 12 can be guided to the semiconductor gas sensor 13. Therefore, it is possible to prevent oil from adhering to or accumulating on the sensor resistor 32 and to extend the service life.
In the lubricant deterioration state detecting device 11, a valve 22 for switching the gas to be guided to the semiconductor gas sensor 13 to either the gas inside the housing 12 or the gas outside the housing 12 is provided in the guide flow path 14. There is. As a result, it is possible to easily switch between performing sensor cleaning that guides the gas outside the housing 12 and performing gas measurement that guides the gas inside the housing 12.

In the lubricant deterioration state detection method, the deterioration state of the lubricant is detected by detecting the target gas generated by the deterioration of the lubricant that lubricates the rolling bearing 15 with the semiconductor gas sensor 13. This makes it possible to improve the detection sensitivity and gas selectivity when detecting the deteriorated state of the lubricant.
In the lubricant deterioration state detection method, the gas in the housing 12 accommodating the rolling bearing 15 is guided to the semiconductor gas sensor 13 by the guide flow path 14, and the concentration of the target gas is detected to detect the deterioration state of the lubricant. Is being detected. This makes it possible to improve the detection sensitivity when detecting the deteriorated state of the lubricant.

In the lubricant deterioration state detection method, the semiconductor gas sensor 13 is cleaned for the cleaning time Tc before guiding the gas in the housing 12 to the semiconductor gas sensor 13. That is, the valve 22 provided in the guide flow path 14 switches from the state of communication with the inside of the housing 12 to the state of communication with the outside of the housing 12, and the pump 16 is used to transfer the gas outside the housing 12 to the semiconductor gas sensor 13. I will guide you to. As a result, even if the gas sensor 13 is operated for a long period of time, it is possible to prevent the semiconductor gas sensor 13 from being contaminated and the detection sensitivity from being lowered, and it is possible to extend the life of the semiconductor gas sensor 13.

In the lubricant deterioration state detection method, the cleaning time Tc is set to be equal to or higher than the value (= Vt / Qp) obtained by dividing the flow path volume Vt of the guide flow path 14 by the flow rate Qp per unit time in the pump 16. As a result, the gas in the guide flow path 14 can be replaced and sufficient cleaning can be performed.
In the lubricant deterioration state detection method, at least one of alcohol, ketone, aldehyde, and organic acid is contained as a target gas, and the concentrations of these are selectively detected. As described above, since it can be detected over the entire carbonyl compound, it is suitable for detecting the deterioration of the lubricant.

"Example"
Next, an example of the lubricant deterioration state detection device 11 will be described.
In the embodiment, as the rolling bearing, one having an inner diameter dimension of 25 mm, an outer diameter dimension of 62 mm, a width dimension of 17 mm, an inner ring rotation, and lubricated with grease is used. The rotation speed was 10,000 r / min, the outer ring temperature was 140 ° C., the radial load was 98 N, and the axial load was 1470 N.

As the grease, the thickener is lithium soap, the consistency is No. 2, the base oil is a mixture of poly-α-olefin and diester, and the kinematic viscosity is 15.9 mm ² / s (40 ° C). Grease was used. A sampling hole having a diameter of 6.5 mm is opened in the axial direction of the housing 12, a tube having an outer diameter of 6 mm and an inner diameter of 4 mm is inserted, and the gas in the housing 12 is sucked. A ceramic filter for removing oil mist was provided between the sampling hole and the sensor. A semiconductor gas sensor is used as the sensor, and the reducing gas removes oxygen on the surface of the metal oxide and detects a decrease in the resistance value generated according to the concentration of the gas. In addition, the outer ring temperature was measured.

By operating the sensor unit at the same time as the start of rotation and intermittently measuring the detected gas concentration, the deterioration state of the lubricant of the rolling bearing was detected. The gas suction path was switched by the valve, and the sensor cleaning for 19 minutes and the gas measurement for 1 minute were repeated.
FIG. 4 is a graph showing the test results of the examples.
(A) in the figure shows the outer ring temperature, and (b) in the figure shows the sensor output. As for the test result, the sensor output increased after 350 hours had passed, and when 380 hours had passed, an abnormal rise in the outer ring temperature was detected and the testing machine stopped. After the test, the rolling bearing had a deteriorated lubricant, which made it difficult to rotate smoothly. Therefore, if the threshold value Eth for the sensor output is set to, for example, about 0.2 to 0.3 V and the testing machine is stopped when the sensor output exceeds the threshold value Eth, the outer ring temperature will not rise abnormally. That is, the testing machine can be stopped before the lubricant deteriorates. Since the sensor output peaks at the initial stage of rotation, it is set as a dead zone for this period.

Next, a comparative example will be described. In the comparative example, gas measurement was carried out using a constant potential electrolytic sensor under the same conditions as in the example.
FIG. 5 is a graph showing the test results of the comparative example.
(A) in the figure shows the outer ring temperature, and (b) in the figure shows the sensor output. The test results showed that the sensor output did not increase before the outer ring temperature rose abnormally. That is, the deterioration of the lubricant progressed before the sensor output increased, and the outer ring temperature rose abnormally.
Therefore, it was confirmed that the examples were superior to the comparative examples in terms of detection sensitivity when detecting the deteriorated state of the lubricant.

<< Modification example >>
In the embodiment, the configuration including one housing 12 has been described, but the present invention is not limited to this, and a configuration including a plurality of housings 12 may be provided.
FIG. 6 is a diagram showing a modified example.
Here, a configuration including two housings 12a and 12b is shown. In this case, a valve 42 (second flow path switching portion) for switching the gas guided to the semiconductor gas sensor 13 to the gas in any one of the plurality of housings 12a and 12b is provided. Since the guide flow path 14, the rolling bearing 15, and the filter 17 have the same configuration in each path, they are designated by the same reference numerals, and detailed description thereof will be omitted. The valve 42 also has a function of switching the gas guided to the semiconductor gas sensor 13 to either the gas inside the housing 12 or the gas outside the housing 12 (first flow path switching unit, flow). Road switching section). That is, the valve 42 is a valve that switches the gas guided to the semiconductor gas sensor 13 to any one of the gas inside the housing 12a, the gas inside the housing 12b, and the gas outside the housing 12.

When the gas measurement is performed on the housing 12a, the gas in the housing 12a is guided to the semiconductor gas sensor 13 after the sensor cleaning is performed. Further, when the gas measurement is performed on the housing 12b, the gas in the housing 12b is guided to the semiconductor gas sensor 13 after the sensor cleaning is performed. In this way, even if the plurality of housings 12 are provided, the gas measurement of the housings 12a and 12b can be performed by one semiconductor gas sensor 13 by switching the flow path by the valve 42. That is, the semiconductor gas sensor 13 can be shared with the plurality of housings 12, and the increase in the number of parts and the increase in cost can be suppressed.

It should be noted that one valve 42 has a function of switching to either the gas inside the housing 12 or the gas outside the housing 12, and switching to the gas inside the housing 12 of any one of the housings 12a and 12b. It has both functions, but is not limited to this. The valve 22 described above may be used to switch between the gas inside the housing 12 and the gas outside the housing 12, and the other valve 42 may be used to switch to any one of the housings 12a and 12b. Further, the present invention includes two housings 12a and 12b, but the present invention is not limited to this, and the present invention can be applied to a configuration including three or more housings 12.

Although the above description has been made with reference to a limited number of embodiments, the scope of rights is not limited thereto, and modifications of the embodiments based on the above disclosure are obvious to those skilled in the art.

11 ... Lubricant deterioration state detector, 12 ... Housing, 12a ... Housing, 12b ... Housing, 13 ... Semiconductor gas sensor, 14 ... Guide flow path, 15 ... Bearing, 16 ... Pump, 17 ... Filter, 21 ... Branch flow path, 22 ... valve, 23 ... filter, 31 ... heater resistance, 32 ... sensor resistance, 33 ... load resistance, 42 ... valve

Claims (10)

A lubricant deterioration state detection device including a semiconductor gas sensor. A housing containing rotatable rolling bearings and
A semiconductor gas sensor that is placed outside the housing and detects the concentration of the target gas,
A guide flow path that communicates with the inside of the housing and guides the gas in the housing to the semiconductor gas sensor is provided.
A lubricant deterioration state detecting device, which detects a deterioration state of a lubricant of the rolling bearing according to a detection result of the semiconductor type gas sensor. The lubricant deterioration state detecting device according to claim 2, wherein the guide flow path includes a filter for removing oil mist contained in a gas. The claim is characterized in that the guide flow path includes a first flow path switching unit that switches the gas that guides the semiconductor gas sensor to either the gas inside the housing or the gas outside the housing. Item 6. The lubricant deterioration state detecting device according to Item 2 or 3. The claim is characterized in that the guide flow path includes a second flow path switching unit that switches the gas that guides the semiconductor gas sensor to the gas in the housing of any one of the plurality of housings. Item 6. The lubricant deterioration state detecting device according to any one of Items 2 to 4. A method for detecting a deteriorated state of a lubricant, which comprises detecting a deteriorated state of the lubricant by detecting a target gas generated by deterioration of the lubricant lubricating the rolling bearing with a semiconductor gas sensor. A claim characterized in that the deteriorated state of the lubricant is detected by guiding the gas in the housing containing the rolling bearing to the semiconductor gas sensor by a guide flow path and detecting the concentration of the target gas. Item 6. The method for detecting a deterioration state of a lubricant according to Item 6. Before guiding the gas in the housing to the semiconductor gas sensor, the flow path switching portion provided in the guidance flow path switches from the communication state with the inside of the housing to the communication state with the outside of the housing, and is determined in advance. The lubricant deterioration state detection method according to claim 7, wherein the semiconductor gas sensor is cleaned by guiding the gas outside the housing to the semiconductor gas sensor using a pump for the cleaning time. .. The lubricant deterioration state detection method according to claim 8, wherein the cleaning time is set to a value equal to or more than a value obtained by dividing the flow path volume of the guide flow path by the flow rate per unit time in the pump. The method for detecting a deteriorated state of a lubricant according to claim 6 or 7, wherein the target gas contains at least one of an alcohol, a ketone, an aldehyde, and an organic acid, and the concentration thereof is selectively detected.

Images