JP7637590B2 - Lubricant diagnostic method, lubricant diagnostic device, and lubricant diagnostic system - Google Patents

Description

The present invention relates to diagnostic methods and systems for lubricating oils and machines that use lubricating oils, and in particular to the diagnosis of remaining life of lubricating oils.

For example, diagnosing the properties of lubricants used in rotating parts such as bearings and gears is an important technique for maintaining large rotating machinery. Examples of large rotating machinery include wind power generator gearboxes, air compressors, ships, and power generation turbines. Depending on the purpose of use, lubricants are classified into various types, such as engine oil, turbine oil, hydraulic oil, bearing oil, sliding surface oil, gear oil, compressor oil, and cutting oil.

Figure 1 shows a list of additives added to various lubricants. As shown in Figure 1, various additives are mixed into each type of lubricant to ensure that they meet the required performance.

Regarding the assessment of lubricant performance, Patent Document 1 discloses a method for assessing the sludge generation potential of new oil. Patent Document 2 discloses a method for estimating the degree of lubricant deterioration in which the lubricant used in rotating machinery is filtered through a membrane filter, a color measurement process is performed to acquire color information of the filter, and the RPVOT remaining rate of the lubricant is estimated based on the color information acquired in the color measurement process and a calibration curve created in a creation process. Patent Document 3 discloses outputting the color of the lubricant as sensor information, and judging the degree of abnormality of the lubricant and the gearbox based on the sensor information and a reference value established for each piece of sensor information.

JP 2003-35706 A JP 2016-20864 A JP 2020-12690 A

In recent years, machine condition monitoring often adopts a strategy that minimizes the life cycle cost of the machine. Large machines such as power generation turbines use large amounts of lubricating oil, and changing the lubricating oil requires stopping the machine, which has negative aspects such as power generation loss and production stoppage. In addition, it is necessary to pay for purchasing and shipping new oil, the oil change work, and the disposal of oil, so it is desirable to use the lubricating oil for as long as possible. Lubricating oil property diagnosis can be broadly divided into two types: (1) oxidative deterioration of the lubricating oil over time, and (2) contamination by external contaminants such as water, dust, and wear powder.

(1) Oxidative deterioration of lubricating oil is known to occur as a result of the consumption of antioxidants contained as additives, followed by oxidation of the base oil. Oxidative deterioration of lubricating oil leads to a decrease in wear resistance, changes in viscosity and viscosity index, a decrease in rust prevention properties, and a decrease in corrosion prevention properties. As a result, wear and material fatigue in the gearbox can be accelerated.

The increase in acidity associated with the oxidative deterioration of lubricating oil is observed as an increase in the total acid number. As oxidation of lubricating oil progresses, the deterioration products of the lubricating oil precipitate in the oil, and organic deposits called sludge or varnish (also called varnish) may form. The formation of sludge or varnish increases the likelihood of machine failure. For example, valves and bearings may stick, and oil filters and piping may become clogged. This can result in valve failure, orifice clogging, bearing wear, and reduced oil cooler performance. Sludge and varnish are unstable in oil, and can accelerate deterioration and accumulate in areas of the machine that are locally overheated, or precipitate suddenly in low-temperature areas.

As a technique for measuring the amount of sludge generated in oil, Patent Document 1 discloses a technique for determining the RPVOT (Rotating Pressure Vessel Oxidation) remaining rate of lubricating oil that has been forcibly deteriorated through an oxidation deterioration test, and judging the generation of sludge in the lubricating oil. RPVOT is a test method recommended in the control items of ASTM D4378, which is related to the management of the deterioration degree of lubricating oil, and is a value indicating the time (induction time) until the lubricating oil being measured begins to rapidly absorb oxygen. ASTM D4378 defines the RPVOT remaining rate as the value obtained by dividing the RPVOT value of deteriorated oil by the RPVOT value of new oil, and recommends that the RPVOT remaining rate be controlled so that it does not fall below 25%. RBOT (Rotating Bomb Oxidation Stability Test) is the old name of RPVOT, and has the same meaning.

Patent document 2 describes a method for estimating the degree of deterioration of a lubricant by measuring the color remaining on a filter when degraded lubricant is filtered through the filter.

(2) Contamination of lubricating oil occurs due to water, dust, and wear particles generated by rotating parts. Water contamination can cause a decrease in lubricating performance due to changes in the viscosity of the lubricating oil, as well as corrosion, rust, and material deterioration of metal parts. Dust itself rarely causes fatal breakdowns, but it can cause an increase in metal wear particles. Wear particles are known to cause fatal breakdowns of machinery depending on their size.

The lubricating oil of rotating machinery such as gas turbines and gearboxes is sometimes sampled in small amounts at predetermined intervals and sent to an analysis center for analysis of viscosity, contamination level, total acid number, metal concentration, etc., to monitor its properties. In addition, status monitoring is performed using a group of sensors (for example, sensors for output, generator speed, power generation, oil temperature, oil pressure, acceleration, etc.) installed in wind turbines, power plants, engines, etc.

Conventional lubricant property diagnostic technology, for example, Patent Document 3 shows that the reduction (degree of consumption) of additives in a lubricant, which is an indicator of lubricant deterioration, can be determined from the color measured by an optical sensor.

In oil maintenance for large machinery, standards for viscosity, total acid number, water content, contamination level (mass method or ISO code), and elemental concentrations such as iron, copper, and phosphorus are often established, along with various standardized measurement methods. For example, known management standards for viscosity are that within 10% of the viscosity of new oil is the acceptable value, for total acid number 0.2 mg KOH/g or less, for water content 200 ppm or less, and for contamination level (mass method) 10 mg/g or less. Management standards vary depending on the type of machine, the type of lubricant product, etc.

Recent improvements in the quality of lubricants, especially base oils, have made viscosity less susceptible to change over time and improved viscosity indices. As a result, there is a trend toward placing emphasis on total acid number and contamination level as management indicators for lubricants.

Lubricating oils contain various additives to maintain their lubricating performance. For example, when the lubricating conditions are severe, such as when the pressure at the contact points is high, the sliding speed is low, or the viscosity of the oil is too low, the film of lubricating oil between the friction surfaces becomes thin, the frictional resistance increases, and wear occurs. This state is called boundary lubrication, and in extreme cases, seizure occurs. Additives work to reduce friction and wear in such boundary lubrication conditions, and examples of these include oiliness agents, anti-wear agents, and extreme pressure additives (extreme pressure agents), which are sometimes collectively called load-bearing additives. Other additives include, for example, antioxidants and defoamers. It is necessary for additives to be contained in a certain ratio (concentration) of the lubricating oil in order to maintain the desired lubricating performance.

Lubricants are composed of base oils that form an optimal lubricating film for machines, and additives that improve functions such as lubrication, extreme pressure, rust prevention, and antifoaming. In particular, almost all lubricants contain antioxidants to prevent a decrease in lubricity due to oxidation of the base oil and an increase in the risk of rust and corrosion due to an increase in the acidity of the lubricant. If the concentration of antioxidants falls below a certain level, there is a problem in that the viscosity and acidity of the lubricant will rise sharply.

Problems with lubricating oil include sludge and varnish (also called varnish). Both sludge and varnish are decomposition products that are formed when components of the lubricating oil are oxidized and precipitate in the oil.

There are several definitions for sludge, but it is a substance that turns into a mud-like substance when lubricating oil is used for a long period of time. It is a general term for impurities that have been mixed into the oil and precipitated, and products of deterioration of the lubricating oil that can no longer be dissolved and precipitate.

There are several definitions of varnish, but it is a sticky oil film of dirt that forms on metal surfaces. In lubricating oils, varnish is a type of sludge, formed when additives deteriorate and their precursors polymerize to form an adsorbed film on the metal surface. Unlike sludge, varnish forms a hard film that may not be easily removed.

All of these are known to cause malfunctions in machines that use lubricating oil. For example, issues include valves tripping (not moving according to control instructions) and bearing malfunctions. Sludge and varnish tend to precipitate in places where the lubricating oil is cooled, so their precipitation in cooling system piping and tanks has been an issue. In addition, even if the temperature is high during operation, when the temperature drops during shutdown, oil deterioration products precipitate, causing malfunctions when the machine is restarted.

The formation of sludge and varnish is accelerated by localized overheating in the machine. For example, lubricating oil dissolves a few percent of air. Pressurization and release of pressure in the machine causes air bubbles to form and adiabatic compression of the bubbles. It is known that localized overheating occurs due to pressure differences in compressed air, leading to the formation of precursors of sludge and varnish. Temperatures can rise to over 500°C, enough to carbonize the lubricating oil in an instant, but this cannot be observed by measuring the temperature on the machine. It is also known that static electricity is generated and electrostatic discharge occurs when the flow rate of the lubricating oil is fast in filters and piping. When static electricity is discharged, temperatures can reach over 1000°C locally, making it easy for varnish to form.

For example, in the case of gas turbines, the combustion temperature of gas turbines is rising, and turbine oil is required to have thermal stability (oxidation stability). The amount of oil tends to decrease, and higher oxidation stability is required. To improve oxidation stability, highly refined base oils and synthetic base oils are being used, but base oils with high oxidation stability tend to be prone to varnish formation. This is because varnish is formed by the precipitation of oxidative decomposition products of oil components, and base oils with high oxidation stability have low solubility of varnish and varnish precursors.

While it is desirable to use lubricating oil for as long as possible, any abnormal deterioration or contamination must be promptly changed and the equipment inspected. This has made it necessary to predict when sludge and varnish will form in the oil, but this has not previously been easy to predict.

The RPVOT method, which is a method for predicting the formation of sludge and varnish in oil, had the problem that it took a long time in the laboratory to obtain results.

As an indicator of the amount of sludge and varnish produced in oil, there are methods to filter the lubricating oil and measure the weight of the solids, or to filter it through a filter, dry the filter, and measure the coloration, but both of these require the lubricating oil to be sampled from the machine and evaluated in a laboratory or office, and there is no way to perform real-time measurements using a machine. Measuring the degree of contamination of lubricating oil (mass method) is significant in that it measures the amount of precursors to sludge and varnish, but because it requires filtering, it is difficult to easily obtain results on the spot where the oil is sampled, and there are also problems with not being able to perform online measurements.

It is necessary to optimize the replacement period of lubricants by monitoring the consumption of additives such as antioxidants in the lubricants and the increase in the acidity of the lubricants while the machine is in use, calculating the remaining life of the lubricants, and continuing to operate the machine without changing the lubricants if the condition of the lubricants is good, and changing the lubricants earlier if the condition of the lubricants is poor.

The objective of this invention is to provide a technology that can easily determine the formation of sludge and varnish in oil.

One aspect of the present invention is a method for diagnosing lubricants containing additives used in machines, which is characterized in that it is possible to convert at least one piece of data selected from among information showing the relationship between the first result and the second result, information showing the relationship between the first result and the third result, and information showing the relationship between the second result and the third result, based on a first result that is a result of a total acid number measurement of the lubricant that is obtained separately in advance, a second result that is a result of a sludge/varnish generation amount measurement of the lubricant that is obtained separately in advance, and a third result that is a result of an optical measurement of the lubricant that is obtained separately in advance, based on the information, into at least one piece of data selected from among first data based on the result of a total acid number measurement of the lubricant that contains additives used in the machine, second data based on the result of a sludge/varnish generation amount measurement of the lubricant that contains additives used in the machine, and third data based on the result of an optical measurement of the lubricant that contains additives used in the machine.

A more specific example is to perform at least one of the following: setting a first threshold value, which is a threshold value of the total acid number for controlling the amount of sludge/varnish produced, based on information showing the relationship between the first result and the second result; and setting a second threshold value, which is a threshold value of the optical measurement result for controlling the amount of sludge/varnish produced, based on information showing the relationship between the first result and the second result and information showing the relationship between the first result and the third result.

A more specific example is a diagnostic device for lubricants containing additives used in machines, which includes a storage device that stores at least one of the first threshold value and the second threshold value, a sensor that acquires third data based on the results of optical measurement of the lubricants containing additives used in the machines, and the third data, either directly or after conversion, is compared with at least one of the first threshold value and the second threshold value, and the diagnostic device for lubricants displays or notifies based on the comparison result.

Another preferred aspect of the present invention is a diagnostic device for lubricants containing additives used in machines, characterized in that it has a correlation database that records at least one of information indicating the relationship between the first result and the third result and information indicating the relationship between the second result and the third result, based on a first result that is a result of a total acid number measurement of the lubricant separately obtained in advance, a second result that is a result of a sludge and varnish generation amount measurement of the lubricant separately obtained in advance, and a third result that is a result of an optical measurement separately obtained in advance, and a data conversion unit that performs conversion between at least one data selected from the first data based on the result of a total acid number measurement of the lubricant containing additives used in the machine and the second data based on the result of a sludge and varnish generation amount measurement of the lubricant containing additives used in the machine, and the third data based on the result of an optical measurement of the lubricant containing additives used in the machine, based on the information.

Another preferred aspect of the present invention is a diagnostic system for lubricants containing additives used in machines, comprising an optical sensor for acquiring color information of the lubricant, at least one database selected from a first database storing the total acid number of the lubricant and a second database storing the measured amount of sludge varnish generation of the lubricant, a data conversion unit for deriving at least one of the total acid number and the measured amount of sludge varnish generation from the color information, and a correlation database referenced by the data conversion unit, the correlation database including at least one of information indicating the relationship between a first result, which is a total acid number quantification result obtained in advance, and a third result, which is color information of the lubricant obtained in advance by optical measurement, and information indicating the relationship between a second result, which is a measured amount of sludge varnish generation obtained in advance, and the third result.

The present invention provides a technology that can easily determine the formation of sludge and varnish in oil. Other issues, configurations, and effects will become clear from the description of the embodiments below.

1 is a table showing types of additives for various lubricants. FIG. 1 is a schematic diagram of the overall configuration of a downwind type wind turbine. FIG. 11 is a graph showing the relationship between contamination level and time. FIG. 2 is a graph showing the relationship between total acid number and time. FIG. 11 is a graph showing the relationship between the degree of contamination and ΔE. FIG. 13 is a graph showing the relationship between the degree of contamination and B. FIG. 2 is a graph showing the relationship between total acid number and ΔE. FIG. 2 is a graph showing the relationship between the total acid number and B. Schematic diagram of a wind turbine lubricant oil monitoring system. 1 is a conceptual diagram of a rotating machine equipped with a lubricant sensor. FIG. 4 is a flow chart showing a lubricant diagnostic process according to an embodiment. FIG. 2 is a functional block diagram of a central server according to an embodiment. FIG. 2 is a graph showing the relationship between the total acid number of the lubricating oils of the examples and time. FIG. 2 is a graph showing the relationship between the total acid number and ΔE of the lubricating oils of the examples. FIG. 2 is a graph showing the relationship between total acid number and time in the examples. FIG. 11 is a graph showing the relationship between ΔE and time in an embodiment. FIG. 1 is a configuration diagram showing an embodiment of a gas turbine. FIG. 2 is a graph showing the results of a correlation between the total acid number and color coordinate (ΔE) of a turbine oil obtained in advance. A graph showing the results of continuous oil color measurements taken by an optical sensor in a gas turbine. FIG. 1 is a diagram showing a configuration in which a branch flow path is provided in the oil flow path of a gas turbine and an optical sensor is installed therein. 1 is a conceptual diagram showing the relationship between viscosity, total acid number, antioxidant concentration, and amount of sludge/varnish.

For example, equipment such as wind turbines must continue to operate stably at a high level for long periods of time, so it is necessary to monitor the properties of the lubricating oil over a long period of time and monitor the formation of sludge in the lubricating oil. In equipment that previously monitored the properties of lubricating oil by sampling the oil and filtering it through filter paper to measure the color of the filter paper, it was difficult to sample the oil and measure the filter paper frequently every day, making it difficult to guarantee the continuity of the measurement data over time.

When there is sufficient antioxidant remaining in the lubricating oil, the antioxidant continues to function and the rate of sludge and varnish formation is low, but as the amount of antioxidant remaining decreases, it is thought that the formation of sludge and varnish accelerates. In other words, as the concentration of antioxidant decreases, the total acid value of the lubricating oil increases, and the acidity of the lubricating oil increases, accelerating the formation of sludge and varnish.

In this way, an increase in the total acid number leads to an increased risk of sludge and varnish formation and an increased risk of rust and corrosion of parts. In addition, the degree of contamination is positively correlated with the concentration of sludge and varnish precursors.

Therefore, it is believed that by monitoring the decrease in antioxidant concentration in lubricating oil, the increase in total acid number, the increase in viscosity, etc., it is possible to indirectly monitor the occurrence of sludge and varnish. It is also believed that it is possible to predict when sludge and varnish will increase rapidly.

In a typical embodiment described in the examples, the remaining life of a lubricant is diagnosed using data from an optical sensor capable of measuring the color coordinate of the lubricant, based on a calibration curve showing the correlation between the measurement results of the rate of increase in total acid number and the rate of increase in contamination level (mass method) and the color coordinate of new and used deteriorated lubricant, which were created in advance using new and used deteriorated lubricant of the same type. This ensures data continuity without the need to collect oil and filter it using filter paper, providing a highly reliable remaining life diagnosis technology. The total acid number of the lubricant was measured by collecting the lubricant in advance and using indicator titration or potentiometric titration.

A preferred example of this embodiment is a diagnostic method for lubricating oil containing additives used in machinery, in which the amount of sludge and varnish produced in the lubricating oil is determined by optical measurement of the lubricating oil using a correlation function between the hue of the lubricating oil and the total acid number, which is determined separately in advance.

Another example is a method for diagnosing lubricants, which is characterized by preparing information showing the relationship between the first result and the second result based on a first result, which is a result of measuring the total acid number of the lubricant or the amount of antioxidant remaining in the lubricant, and a second result, which is a result of optical measurement obtained separately in advance, and making it possible to convert the first data based on the result of measuring the total acid number of the lubricant used in the machine or the amount of antioxidant remaining in the lubricant, and the second data based on the result of measuring the lubricant containing the additive used in the machine by optical measurement, thereby predicting the generation of sludge and varnish in the lubricant.

Yet another example is a diagnostic device for lubricating oil containing additives used in a machine, which is characterized by having a correlation database that records information showing the relationship between a first result, which is a result of a total acid number measurement or a result of measuring the amount of antioxidants remaining in the lubricating oil, obtained separately in advance, and a second result, which is a result of optical measurement, obtained separately in advance, based on the first result and the second result, and a data conversion unit that converts the first data based on the total acid number result of the lubricating oil containing additives used in the machine or the result of measuring the amount of antioxidants remaining in the lubricating oil, based on the information, and the second data based on the result of optical measurement of the lubricating oil containing additives used in the machine, and is characterized by predicting the generation of sludge and varnish in the lubricating oil.

Another example is a diagnostic system for lubricants containing additives used in machinery, comprising an optical sensor that acquires color information of the lubricants, a database that stores a prediction function for sludge and varnish formation in the lubricants using the total acid number measurement results of the lubricants or the measurement results of the amount of antioxidant remaining in the lubricants, a data conversion unit that derives the amount of the additives from the color information, and a correlation database referenced by the data conversion unit, the correlation database being information indicating the relationship between a first result, which is the total acid number measurement results of the lubricants or the measurement results of the amount of antioxidant remaining in the lubricants, and a second result, which is color information of the lubricants previously obtained by optical measurement.

According to this embodiment, it is possible to predict when sludge and varnish will form in the lubricating oil of machines such as gas turbines, wind power generators, and air compressors, and a highly reliable remaining life assessment technology can be provided. Other issues, configurations, and effects will be made clear in the explanation of the embodiment below.

In wind power generators, lubricants and the like are used to reduce the mechanical coefficient of friction between components. In the following examples, a lubricant remaining life assessment technology is explained using a wind power generator's lubricant as an example. One example explained in the examples is a wind power generator diagnostic system that collects information from a wind power generator having a gearbox and a generator, and judges abnormalities in the wind power generator based on the collected information. In order to monitor the state of the wind power generator, this system has a sensor that outputs the properties of the lubricant supplied to the gearbox as sensor information, and a memory unit that stores reference values determined for each piece of sensor information.

<Basic configuration of a wind turbine>
Figure 2 shows a schematic overall configuration diagram of a downwind type wind power generator as an example of a machine to be monitored. In Figure 2, each device arranged in a nacelle 3 is indicated by a dotted line. As shown in Figure 2, the wind power generator 1 includes blades 5 that rotate by receiving wind, a hub 4 that supports the blades 5, the nacelle 3, and a tower 2 that supports the nacelle 3 so that it can rotate in a horizontal plane.

Inside the nacelle 3, there is a main shaft 31 that is connected to the hub 4 and rotates together with the hub 4, a shrink disk 32 that is connected to the main shaft 31, a speed increaser 33 that is connected to the main shaft 31 via the shrink disk 32 and increases the rotation speed, and a generator 34 that generates electricity by rotating the rotor at the rotation speed increased by the speed increaser 33 via a coupling 38.

The part that transmits the rotational energy of the blades 5 to the generator 34 is called the power transmission part, and includes the main shaft 31, the shrink disk 32, the speed increaser 33, and the coupling 38. The speed increaser 33 and the generator 34 are held on the main frame 35.

In addition, one or more lubricating oil tanks 37 are installed on the main frame 35 to store lubricating oil for lubricating the power transmission parts. In addition, a radiator 36 is arranged inside the nacelle 3 on the upwind side of the nacelle bulkhead 30. Cooling water cooled in the radiator 36 using outside air is circulated to the generator 34 and the gearbox 33 to cool them. Although FIG. 2 shows an example of a so-called downwind type wind turbine, it goes without saying that this embodiment can also be applied to an upwind type wind turbine.

In wind turbines, lubricating oil is used in many rotating machines. For example, in Figure 2, lubricating oil is supplied to the main shaft 31, the gearbox 33, the generator 34, and the yaw and pitch bearings (not shown). Blade pitch control is the control of output by changing the pitch angle of the blades according to the wind speed, and yaw control is the control of the nacelle's orientation to make the wind turbine follow the wind direction in order to receive the wind efficiently.

In addition to these power transmission parts, rotating machinery, including rotating machinery for yaw control and pitch control, requires forced circulation of lubricating oil. Lubricating oil reduces friction in the rotating parts of rotating machinery, preventing wear and damage to parts and energy loss. However, if the lubricating oil's lubricating performance decreases due to deterioration over time, or if the lubricating oil becomes contaminated by wear particles, dust, etc., the coefficient of friction increases, increasing the risk of breakdown of the wind turbine generator.

When a wind turbine breaks down, significant loss costs are incurred, including the cost of replacing the broken parts and the loss of power generation revenue during the blackout. Therefore, measures such as early parts ordering by predicting remaining life and detecting signs, and shortening the duration of the blackout are desirable. In particular, the gearbox, which is a critical component, is at increased risk of failure if the performance of the lubricant deteriorates, so technology to estimate the remaining life and replacement timing of the lubricant as early as possible is important.

<Lubricant remaining life evaluation method>
As an index for evaluating the remaining life of lubricating oils, etc., there is a method in which a certain amount of lubricating oil is filtered through filter paper, the filter paper is dried after filtration, and the weight of the residue remaining on the filter paper is measured. This index is used as the degree of contamination (mass method). This explains the remaining life evaluation method for gear oil that contains amine-based and phenol-based antioxidants, phosphorus-based extreme pressure agents, and uses synthetic oil PAO (polyalphaolefin) as the base oil. In this method, the same filter paper and a certain amount of lubricating oil are always used, and the same filtering method and filter paper drying method are used.

Figure 3 shows the relationship between contamination level and time, as a result of measuring the contamination level (mass method) by sampling oil every year from the same wind turbine without changing the oil during that time. The acceptable value for contamination level (mass method) for this wind turbine is 10 mg/100 ml. Based on the measurements up to the third year, it was predicted that the acceptable value for contamination level (mass method) would be reached after five years. The acceptable value for contamination level may differ depending on the type of oil, wind turbine, and machine. As mentioned earlier, contamination level is positively correlated with the concentration of sludge and varnish precursors, so Figure 3 can be considered equivalent to the relationship between the amount of sludge and varnish produced and time.

Here, the mechanism of sludge varnish formation has a direct correlation with the oxidation of the lubricating oil, i.e., it has a correlation with the total acid number of the lubricating oil.

Figure 4 shows the change in the total acid number of the samples taken in Figure 3, showing the relationship between the total acid number and time. The allowable total acid number is 0.25. Based on the measurements up to the third year, it was predicted that the allowable total acid number would be reached after five years. The allowable total acid number may differ depending on the type of oil, wind turbine, and machine.

However, methods such as collecting oil and filtering it with filter paper, or measuring the total acid number by titration, are difficult to apply to online monitoring. For this reason, for example, in offshore wind turbines, operation must be stopped to collect the lubricating oil, and workers must collect the oil. This means that frequent collection is not possible, and there is a risk that abnormalities in the lubricating oil, such as abnormal deterioration, may go unnoticed.

On the other hand, it is known that lubricating oils become discolored due to deterioration such as the consumption of additives. When the antioxidant is consumed, the oxidation of the base oil proceeds more easily, and the total acid number of the lubricating oil increases. At the same time, the concentration of sludge and varnish precursors (degree of contamination) increases, and the degree of contamination (mass method) increases. For example, there are color-based diagnostic methods such as the ASTM color scale. There are also optical sensors that can output the color of the lubricating oil as color coordinates such as RGB. A typical optical sensor can determine the color coordinates of the lubricating oil from the light transmittance. By installing an optical sensor in a machine that uses lubricating oil, it is possible to constantly measure the color of the lubricating oil online.

As a result of the inventor's research, it was found that there is a correlation between the degree of contamination (mass method) and total acid number of the gear oil used, and the color index of the gear oil used, which was determined optically.

Below, we explain an example of estimating the remaining life of a lubricant by using a calibration curve created using the change in the lubricant over time determined from the contamination level (mass method) and total acid number, and color data obtained from measurement data from an optical sensor.

Figure 5 is a graph showing the relationship between the degree of contamination of the lubricating oil (mass method) and the color of the lubricating oil measured by an optical sensor. In this case, the color coordinates of colorless pentane were set to (255, 255, 255), and the color coordinates of the sampled lubricating oil were measured. The color of the lubricating oil measured by the optical sensor is displayed as the color difference (ΔE) calculated in a color space composed of a combination of RGB.

The definition of ΔE is
ΔE=(R ² +G ² +B ² ) ^1/2
R, G, and B represent the three primary colors of light (Red, Green, and Blue) in additive mixing, and are expressed as (R, G, and B) in numerical color coordinates. The wavelengths of the three primary colors of light are R 610 to 750 nm, G 500 to 560 nm, and B 435 to 485 nm.

In addition, the difference between the maximum and minimum values of R, G, and B is defined as MCD and may be used for diagnosis.
MCD = R-B
This is often the case.

RGB chromaticity encoded at 24 bpp (24 bits per pixel) is represented by three 8-bit integers (0 to 255) that indicate the brightness of red, green, and blue. For example, (0, 0, 0) is black, (255, 255, 255) is white, (255, 0, 0) is red, (0, 255, 0) is green, and (0, 0, 255) is blue. In addition to the RGB color system, there are many other ways to express chromaticity, such as the XYZ color system, the L ^* a ^* b ^* color system, and the L ^* u ^* v ^* color system, and these can be mathematically converted and expanded into various color systems, so chromaticity may also be displayed in other color systems. If the color of the lubricant is quantified in terms of chromaticity, the original lubricant color can be displayed on the monitor or display of a computer or monitoring system by converting the chromaticity value.

As shown in Figure 5, there was a high correlation between the degree of contamination (mass method) and ΔE for the lubricants (X, Y, Z) sampled periodically.

Figure 6 shows the correlation between the B value of the lubricant's color coordinates (RGB) and the degree of contamination. Of the lubricant's color coordinates (RGB), the B value changes the most over time, and as shown in Figure 6, the calibration curve obtained from the correlation between the degree of contamination (mass method) and the B value is also effective.

Figure 7 shows a calibration curve showing the correlation between the total acid number of a lubricant and ΔE determined by an optical sensor.

Figure 8 shows a calibration curve showing the correlation between the total acid number of a lubricant and the B value determined by an optical sensor.

Here, the relationship between the degree of contamination (mass method) C of the lubricating oil or the total acid number T of the lubricating oil and the color index (ΔE, B value, etc.) of the lubricating oil as shown in Figures 5 to 8 can be expressed as a function formula as follows.
C=f(ΔE)...(1)
or,
C=f(B)...(2)
T=f(ΔE)...(3)
or,
T=f(B)...(4)
From equations (1) to (4), it can be seen that the following relationships hold:
C=f(T)...(5)

The above C, T, B, and ΔE can be experimentally determined for a specific lubricant. A calibration curve showing the relationship between the degree of contamination (mass method) and total acid number of a lubricant and the color coordinates can also be created using lubricants that have been forcibly oxidized and deteriorated through various oxidation tests known as accelerated deterioration tests for lubricants. Even if the type and initial concentration of the antioxidant are the same, the degree of color change due to deterioration associated with use in a machine may differ if the type of base oil and the types and concentrations of other additives are different. For this reason, a calibration curve showing the relationship between the degree of deterioration of a lubricant and its color must be created for each type of oil.

The color of a lubricant changes due to oxidative deterioration, but also when a large amount of water, fine particles, wear powder, etc. is mixed into the oil. Here, oxidative deterioration of a lubricant is defined as "deterioration," and the phenomenon in which water, fine particles, wear powder, etc. are mixed in from the outside is defined as "contamination." Regarding such deterioration and contamination, for example, it is possible to diagnose on a graph of ΔE and MCD, which are indicators of the color of the lubricant, whether a sample is only deteriorating or whether a certain level of contamination has occurred in addition to deterioration.

In terms of lubricant diagnosis, if the above contamination occurs, the diagnosis result will be that the lubricant should be changed immediately and the machine inspected, since, for example, water contamination can cause corrosion and rust in the machine, and fine particles and wear powder can cause damage to gears and bearings. A lubricant remaining life assessment will be carried out if there is no contamination or if the contamination is minor.

An optical sensor for measuring the properties of a lubricant is installed on a part that uses lubricant, such as a wind turbine gearbox, and the remaining life of the lubricant can be calculated using the sensor data and a calibration curve previously calculated from the correlation between the degree of contamination of the lubricant (mass method) or the total acid number and color of the lubricant.

In this way, an optical sensor installed in the gearbox lubricant detects the color of the lubricant, and based on that color information, the degree of deterioration and abnormal contamination of the lubricant is determined in real time. Depending on the results of this determination, the system prompts the user to collect lubricant for detailed lubricant analysis at an appropriate time before the gearbox breaks down.

The relationship between the color information from the optical sensor and the degree of abnormality in the lubricant (impurity concentration, degree of oxidation, etc.), and the relationship between the color of the lubricant and the degree of contamination (mass method) and total acid number of the lubricant are experimentally determined in advance and stored as a database. This makes it possible to prevent breakdowns by properly changing the lubricant, filters, or parts, and also enables efficient management of wind turbines by quickly taking measures such as repairs.

The following describes in detail the embodiments of the present invention with reference to the drawings. However, the present invention should not be interpreted as being limited to the description of the embodiments shown below. It will be easily understood by those skilled in the art that the specific configuration can be changed without departing from the concept or spirit of the present invention.

In the configuration of the invention described below, the same parts or parts having similar functions are designated by the same reference numerals in different drawings, and duplicate explanations may be omitted.

When there are multiple elements with the same or similar functions, they may be explained by using the same reference numeral with different subscripts. However, when there is no need to distinguish between multiple elements, the subscripts may be omitted.

The designations "first," "second," "third," and the like in this specification are used to identify components and do not necessarily limit the number, order, or content. Furthermore, numbers for identifying components are used in different contexts, and a number used in one context does not necessarily indicate the same configuration in another context. Furthermore, this does not prevent a component identified by a certain number from also serving the function of a component identified by another number.

The position, size, shape, range, etc. of each component shown in the drawings, etc. may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings, etc.

The following embodiment describes a wind turbine generator having a gearbox and a generator, and a wind turbine generator diagnostic system that collects information from the wind turbine generator and judges abnormalities in the wind turbine generator based on the collected information. When measuring and diagnosing the color of the lubricant supplied to the gearbox using a sensor, an example is described in which more accurate sensor diagnosis is performed by using the correlation between the color information and the degree of contamination (mass method) and total acid number of the lubricant.

In the embodiment, in order to monitor the lubricating oil supplied to the mechanical drive unit of the wind turbine generator, various sensors, including an optical sensor installed in the lubricating oil of the gearbox, detect the acceleration of the gearbox to grasp the lubricating oil properties and the state of the rotating machine, and based on the sensor information (a numerical value indicating the physical and chemical state of the lubricating oil), determine the degree of abnormality of the lubricating oil and the state of the rotating machine in real time.

The wind turbine generator diagnostic system then recommends lubricant sampling, lubricant change, filter replacement, and part replacement at an appropriate time before the gearbox fails, depending on the results of the judgment. The system is equipped with an input device, a processing device, a storage device, and an output device. The storage device stores the correlation between the change in contamination level (mass method) and total acid number over time and the chromaticity, which is optical sensor data, and the processing device estimates the time when the contamination level (mass method) or total acid number of the lubricant, which is determined from the chromaticity characteristics of the lubricant, will reach or exceed a reference value, based on the optical sensor data that measures the chromaticity of the lubricant.

Also, the embodiment is a wind power generator diagnostic system and method using an optical lubricant sensor, which uses a server equipped with a processing device, a storage device, an input device, and an output device. In this method, the following steps are executed: a first step of acquiring color data of the lubricant in the wind power generator in order to grasp the properties of the lubricant; a second step of measuring the contamination level (mass method) and total acid number of the sample; a third step of storing the measured contamination level (mass method) and total acid number in a chronological order in the storage device to obtain additive concentration data; and a fourth step of estimating the time when the contamination level (mass method) and total acid number will reach a predetermined threshold value by processing the contamination level (mass method) and total acid number data by the processing device.

(1. Overall System Configuration)
As an example of a machine for performing lubricant diagnosis, a schematic diagram of a lubricant monitoring system for a wind power generator having a lubricant supply system is shown in Figure 9. For the purpose of explanation, Figure 9 shows the nacelle 3 portion of the wind power generator 1 shown in Figure 2. Inside the nacelle 3 are a main shaft 31, a gearbox 33, a generator 34, and bearings such as yaw and pitch bearings (not shown), which are supplied with lubricant from a lubricant tank 37.

As shown in FIG. 9, multiple wind power generators 1 are usually installed on the same site, and are collectively referred to as farm 200a. Various sensors (not shown) are installed in the lubricating oil supply system of each wind power generator 1, and sensor signals reflecting the state of the lubricating oil are aggregated in a server 210 in the nacelle 3. In addition, the sensor signals obtained from the server 210 of each wind power generator 1 are sent to an aggregation server 220 arranged for each farm. Data from the aggregation server 220 is sent to a central server 240 via a network 230. Data from other farms 200b and 200c is also sent to the central server 240. In addition, the central server 240 can send instructions to each wind power generator 1 via the aggregation server 220 and the server 210.

2. Sensor Arrangement
10 is a conceptual diagram of a rotating machine equipped with a lubricant sensor. Lubricant is supplied to a rotating machine 302 from a lubricant supply device 301 such as a pump. The lubricant supply device 301 is connected to a lubricant tank 37 to receive the supply of lubricant. The rotating machine 302 may include, for example, a gearbox 33 and other parts where mechanical contact occurs, as well as a power transmission unit for performing yaw and pitch control.

The sensor group 304 is arranged in the lubricant flow path, etc., to detect the state of the lubricant. In the first embodiment, the measurement unit 303 is provided in a flow path (branch line) branched from the lubricant flow path connected to the lubricant drain of the rotating machine 302, and a part of the lubricant is introduced into the measurement unit 303, and the sensor group 304 is installed in the measurement unit 303. It is preferable to provide the branch line near the end of the lubricant path in order to monitor the deterioration state of the lubricant. The measurement unit 303 is not provided in the main lubricant flow path (circulation line) in order to adjust the flow rate of the lubricant in the measurement unit 303 to a flow rate suitable for detecting the state of the lubricant. In this way, the hydraulic pressure can be adjusted by using a branch line that branches off from the circulation line and is arranged in parallel with the circulation line, and adjusting the bending shape and thickness of the branch line.

The lubricating oil discharged from the rotating machine 302 returns to the lubricating oil tank 37 via the oil filter 305. The mesh diameter of the oil filter 305 is 5 to 50 μm.

The terms upstream and downstream are sometimes used to describe the relative positions along the lubricating oil flow path. The lubricating oil moves relatively from upstream to downstream. In the case of Figure 10, the lubricating oil supply device 301 is located upstream, the oil filter 305 is located downstream, and the measurement unit 303 is located between them. Note that the arrangement of each element is not limited to the configuration of Figure 10; for example, the lubricating oil tank 37 may be located between the rotating machine 302 and the measurement unit 303, as described below.

The sensor group 304 measures various parameters of the lubricating oil. For example, physical quantities include color measured by an optical sensor, as well as temperature and oil pressure. Instead of or in addition to the optical sensor, a sensor may be provided that measures electrical properties of the lubricating oil, such as dielectric constant and conductivity. Temperature, oil pressure, etc. can be measured using known sensors. The condition of the lubricating oil can be evaluated based on the changes in these parameters over time. These sensors for temperature, etc. are not essential, but it is preferable to provide them in order to detect the condition of the lubricating oil in more detail.

In the embodiment, the sensor group 304 includes an optical sensor equipped with a visible light source and a light receiving element. The optical sensor measures the visible light transmittance of the lubricant and outputs chromaticity information (R, G, B values) of the lubricant. From the acquired chromaticity data, the amount of remaining additives in the lubricant is calculated, and a deterioration diagnosis and remaining life diagnosis are performed. In a diagnosis based on sensor data, a diagnosis is performed based on sensor data from an optical sensor or data from an optical sensor and one or more other types of sensors.

As lubricating oil is used, its antioxidants become depleted and its quality deteriorates, and it no longer performs its original function. For this reason, maintenance such as replacement is required depending on the deterioration of the quality. In order to know the timing of such maintenance, it is useful for the efficiency of maintenance management to be able to monitor the data that can be collected by the sensor group 304 from a remote location. The data collected by the sensor group 304 is collected, for example, by the server 210 in the nacelle 3, and then sent via the aggregation server 220 that aggregates data within the farm 200 to the central server 240 that aggregates data from multiple farms.

The data to be aggregated may include not only data related to the lubricant, but also data indicating the operating status of the wind turbine. For example, data such as an acceleration sensor that detects vibrations of the wind turbine 1 (the higher the value, the faster the lubricant deteriorates), wind turbine output value (the higher the value, the faster the lubricant deteriorates), actual operating time (the longer the value, the faster the lubricant deteriorates), machine temperature (the higher the value, the faster the lubricant deteriorates), shaft rotation speed (the faster the lubricant deteriorates), and lubricant temperature (the higher the value, the faster the lubricant deteriorates). These data can be collected from sensors of known configurations installed in various places on the wind turbine, or from control signals from the device.

(3. Lubricant diagnosis flow)
FIG. 11 is a flow diagram showing the lubricant oil diagnosis process according to the embodiment. The process shown in FIG. 11 is performed under the control of the server 210, the aggregation server 220, or the central server 240 in FIG. 9. In the following example, it is assumed that the central server 240 performs the process. Functions such as calculation and control are realized by the processor executing software stored in the server's storage device, in cooperation with other hardware to perform the specified process. Note that functions equivalent to those configured by software can also be realized by hardware such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC).

When the central server 240 performs control, since it has multiple wind power generators 1 under its control, the following process is performed for each wind power generator. This process is basically a repetitive process, and the start timing is set by a timer or the like; for example, the process starts at midnight every day (S601). The central server 240 can also perform the process at any timing in response to instructions from the operator.

In step S602, the central server 240 checks when it is time to change the lubricant. The initial value for the change time is, for example, initially set to the remaining life, assuming that the lubricant is operating at its design temperature. This change time can be updated later in step S610 based on actual measurement data.

If it is time to change the lubricant, the lubricant is changed in step S603. Since changing the lubricant is usually done by a worker, the central server 240 displays and notifies the worker when and what to change.

If it is not time to change the lubricant, in step S604, the central server 240 diagnoses the properties of the lubricant using sensor data. In addition to the lubricant color information obtained by the optical sensor, the sensor data can include temperature, oil pressure, and the concentration of particles contained in the lubricant. The data measured by the sensor group 304 is sent to the central server 240, and the central server evaluates the properties of the lubricant by, for example, comparing the parameters obtained from the sensors with predetermined reference values. The central server stores in advance the correlation between color and contamination level (mass method), the correlation between color and total acid number, the changes in the R, G, and B values when the antioxidant in the lubricant is consumed (the additive decomposes to generate oxidation products), and the changes in the R, G, and B values when wear particles are generated in the lubricant, as shown in Figures 3 to 8, and uses these to compare with the sensor data. In addition to a predetermined threshold value, the change in the sensor information per unit time can be used as the reference value.

Figure 12 shows the programs and data structure stored in the central server 240. The central server 240, like a typical server, is equipped with an input device 1001, an output device 1002, a processing device 1003, and a storage device 1004. Figure 12 shows the programs and data structure stored in the storage device 1004.

The storage device 1004 of the central server 240 stores the following data: a correlation database (DB) 241 that stores the correlation between the chromaticity (ΔE and B) shown in FIG. 7 and FIG. 8 and the total acid number determined by indicator titration or potentiometric titration, which has been experimentally determined in advance; a total acid number DB 242 of the lubricating oil of an actual machine (e.g., a wind power generator) measured by indicator titration or potentiometric titration; and a chromaticity DB 243 that stores sensor data acquired by an optical sensor in chronological order. The correlation DB 241 may store the correlation data of FIG. 5 and FIG. 6, which shows the correlation between the degree of contamination and chromaticity, instead of or in addition to the data of FIG. 7 and FIG. 8. By referring to the correlation DB 241, it is possible to convert between the total acid number, chromaticity, and degree of contamination (amount of sludge and varnish produced).

The correlation DB 241 may store, for example, the functions shown in formula (3) or formula (4), or the data shown in Figures 7 and 8. The data conversion program 244 can use the information stored in the correlation DB 241 to convert the data in the chromaticity DB 243 into the total acid number of the lubricating oil measured by indicator titration or potentiometric titration. The data in the total acid number DB 242 stores, for example, the data shown in Figure 4.

If the data in the color DB 243 and the total acid number DB 242 are time-series data relating to the same measurement target, the converted data 245 obtained by the data conversion program 244 has continuity with the data in the total acid number DB 242, so that two different measurement methods can be used as a continuous series of time-series data.

The storage device 1004 also includes a diagnostic program 246 that controls the entire lubricant diagnostic process shown in FIG. 11.

Returning to FIG. 11, if the diagnosis results in steps S605 and S606 indicate an abnormality, the lubricant is changed in step S603. Specifically, the lubricant is changed by notifying the person in charge of managing the change of the lubricant that a change is necessary. If no abnormality is found, step S609 is performed.

In process S605, for example, if all the R, G, and B values of the optical sensor are lower than a predetermined threshold, it is determined that there is a contamination abnormality. In this type of determination, blackening of the lubricant oil is detected. However, data from a conventional sensor may also be used to determine contamination abnormalities.

In S606, the chromaticity data is converted into an estimated value of the total acidity of the lubricant containing the additive used in the machine, for example, using the correlation between the total acidity and chromaticity shown in Figures 7 and 8. If the total acidity calculated from the chromaticity measured by the optical sensor exceeds a predetermined threshold, it is determined that there is an abnormality in the degree of additive degradation. It is also possible to determine that there is an abnormality in the degree of additive degradation when the chromaticity is smaller than a predetermined threshold, without calculating the total acidity from the chromaticity.

In process S609, chromaticity measurement data and the like are input to the central server 240, and the chromaticity measurement data is stored in chronological order in the chromaticity DB 243.

From the perspective of preventive and planned maintenance of wind turbines, it is desirable to perform predictive diagnosis of lubricant deterioration based on the change in the total acid number of the lubricant before it is determined that there is an abnormality.

As described above, by using the results of the total acid number measurement of the lubricant measured by indicator titration or potentiometric titration and the color information of the lubricant measured by an optical sensor, it is possible to obtain time-series data on the normality of the lubricant, and by knowing the remaining lifespan of the lubricant, it is possible to detect the end of its lifespan early. Therefore, by performing maintenance such as appropriate lubricant changes, it is possible to prevent abnormalities in wind turbine generators. It is also possible to optimize the lubricant change cycle. Furthermore, the antioxidant concentration can be measured by a simple method, and by installing an optical sensor inside the nacelle, it is possible to remotely monitor the increase in the total acid number of the lubricant online.

(4. Lubricant remaining life assessment)
In this embodiment, in the replacement time estimation and update process S610 in FIG. 11, the total acid number of the lubricant used in the wind turbine is determined by indicator titration or potentiometric titration, and the individual color coordinates of the same lubricant sample are determined by an optical sensor. Based on information obtained from the correlation between the total acid number and the color coordinates, the total acid number is determined from the color measurement of the lubricant, and the remaining life of the lubricant is also calculated.

For the same model of lubricant, we obtained new oil (A), as well as samples that had been used in a wind turbine for one year (B), two years (C), and three years (D).
For these lubricating oil samples (A) to (D), the tendency of the total acid number to increase over time was confirmed by potentiometric titration, as shown in FIG.

As shown in FIG. 13, the total acid value of this lubricant is set to 0.3 mg KOH/g as the threshold value. This is because the correlation function between the total acid value and the contamination level (mass method), which is an index of the amount of sludge and varnish generated, is calculated in advance, and it is possible to predict the generation of sludge and varnish from the color coordinates of the lubricant. When the total acid value of this lubricant reaches 0.3, the contamination level of this lubricant is 10 mg/100 ml. In other words, the life of this lubricant is from the start of use to the time when the total acid value reaches the threshold value. If a threshold value for the contamination level (mass method) is set, the life of this lubricant is from the start of use to the time when the contamination level (mass method) reaches the threshold value. If the threshold values for the total acid value and the contamination level (mass method) are reached at different times, the life of this lubricant is the time when either one of them reaches the threshold value. In this way, a threshold value for the total acid value for controlling the amount of sludge and varnish generated can be set, and the total acid value can be indirectly calculated from the color.

On the other hand, color measurements were performed on samples (A) to (D) using, for example, the optical sensor disclosed in Patent Document 3. At this time, the color coordinates of new oil (A) were standardized to (255, 255, 255). The ΔE value was calculated from each color coordinate. Regarding the standardization method of color coordinates, it was possible to perform evaluation even when the color coordinates of colorless liquids, such as additive-free base oils and colorless solvents, were set to (255, 255, 255).

Figure 14 is a graph showing the relationship between the ΔE value and the total acid number, based on the correlation function (e.g., the relationship of formula (3)) between the total acid number quantitative result (first result) obtained by potentiometric titration and the lubricant diagnostic result (second result) obtained in advance by optical measurement. The relationship between the total acid number and the ΔE value, as shown in Figure 14, was clarified.

From Figure 14, it was found that when the total acid number is 0.3, the ΔE value is 200. In other words, based on the information showing the relationship between the first result and the second result, a ΔE threshold value for controlling the value of the total acid number can be set. Since there is a correlation between the total acid number and the amount of sludge and varnish produced, this means that a chromaticity threshold value has been set in order to control the value of the amount of sludge and varnish produced.

In this way, it was found that by using Figure 14 as a calibration curve, the total acid number obtained by potentiometric titration can be obtained from the color coordinates of the lubricating oil measured by an optical sensor. For example, the calibration curve shown in Figure 14 is stored in the correlation DB 241 in Figure 12.

In this way, by using correlation DB241, in process S610, it is possible to make compatible data based on the total acid number quantitative result (first result) obtained in advance by potentiometric titration and data based on the lubricant diagnosis result (second result) obtained in advance by optical measurement.

Figure 15 is a graph showing the relationship between total acid number and time to explain the principle of remaining life assessment in the embodiment. In this embodiment, the total acid number of sampled lubricant oil samples is measured by potentiometric titration in the period 1501 from when new oil was used in a wind turbine until two years have passed, and data 1502 is obtained. From the second to fourth years, the color of the lubricant oil is measured using an optical sensor, and the color information is converted by the data conversion program 244 using the correlation DB 241, so that the total acid number 1503 can be obtained in almost real time. As shown in Figure 15, from the data 1502 and the total acid number 1503, it can be predicted using well-known methods such as function approximation and extrapolation that the remaining life 1504 until the total acid number exceeds 0.3 at the four-year point is 0.5 years.

The remaining life thus determined may be shown to the user, for example, on a display in step S611. In step S612, the optical sensor output may be converted to a color corresponding to the color information of the lubricant and displayed.

In Figure 15, color information data based on an optical sensor is converted into total acid number based on potentiometric titration. Conversely, the total acid number based on potentiometric titration can also be converted into color information data based on an optical sensor using the calibration curves in Figures 7 and 8.

In Figure 16, the contamination level (mass method) is measured in a wind turbine from the time new oil was used until two years have passed 1501, and the contamination level (mass method) is converted to ΔE to obtain data 1602. From the second to fourth years, an optical sensor is used to measure the color of the lubricating oil, making it possible to obtain ΔE data 1603 in near real time.

As described above, in this embodiment, the total acid number data and contamination level (mass method) data based on potentiometric titration can be converted into data based on color information obtained by optical measurement, making it possible to monitor the properties of the lubricating oil based on the same standards over a longer period of time. This makes it possible to perform more accurate remaining life diagnosis based on data showing changes in the lubricating oil properties over time.

Figure 17 is a block diagram showing an embodiment of a gas turbine, and is an example of monitoring turbine oil.

The turbine 700 is connected by the turbine shaft 701. Turbine oil is stored in the main oil tank 702, sent to the oil cooler 703 by the oil pump 712, and then supplied to the turbine shaft 701. The turbine oil is supplied in the direction of the arrow 714, and then returns to the main oil tank 702 through the return flow path 705.

In this embodiment, an optical sensor 704 for monitoring changes in the properties of the turbine oil was installed between the oil cooler 703 and the turbine shaft 701, and acquired color information of the lubricating oil.

As explained in equations (1) to (5), by utilizing the mutual correlation between the total acid number, the amount of sludge and varnish produced, and the color information, a threshold value for the total acid number for controlling the amount of sludge and varnish produced can be set in an associated storage device and compared with the total acid number calculated indirectly from the color information of the optical sensor 704. To achieve this, the optical sensor 704 can be provided with a data conversion means for color information and total acid number. Alternatively, a threshold value for color information for controlling the amount of sludge and varnish produced can be set in an associated storage device and compared directly with the color information.

Figure 18 is a graph showing the results of a pre-calculated correlation between the total acid number of turbine oil and color coordinate (ΔE). The reference value of the total acid number of this turbine oil is 0.2 (mg KOH/g), and the ΔE value when the total acid number is 0.2 is 240. Similarly, for turbine oil, the results of a pre-calculated correlation between the total acid number of turbine oil and color coordinate (B) can be obtained, as in Figure 8.

Figure 19 shows the results of continuous measurement of oil color using the optical sensor 704 in the gas turbine shown in Figure 17. The plot shows the value of 2051 two years after the start of use. By extrapolating the ΔE value from the start of use until two years have passed, it was predicted that the total acid number would reach 0.2 after 3.8 years. Similarly, when the B value of the color coordinate was used, it was possible to determine that the total acid number would reach 0.2 after 3.8 years.

Figure 20 shows a configuration in which a branch flow path is provided in the oil flow path of a gas turbine and an optical sensor 704 is installed. The difference from Figure 17 is the placement of the optical sensor 704. With this configuration, it was also possible to monitor the increase in total acid number associated with oil use.

As explained in the above examples, the configuration of the examples makes it easy to determine the formation of sludge and varnish in oil by indirectly determining it through the total acid number.

Figure 21 is a conceptual diagram showing the relationship between viscosity, total acid number, antioxidant concentration, and sludge/varnish amount, and these correlations can be used to estimate the relative values. When the antioxidant concentration decreases, oxidation is promoted, total oxidation increases, sludge/varnish is produced, and viscosity increases. A threshold value 2101 is set for the amount of sludge/varnish before the viscosity starts to increase, encouraging the oil to be changed. This timing can be detected by indirectly measuring the total acid number from the color of the oil.

In the above embodiment, a wind power generator and a gas turbine are used as examples of rotating machines, but this embodiment can also be applied to the deterioration diagnosis of additives in lubricating oils for rotating machines such as steam turbines, nuclear power generators, thermal power generators, geared motors, railway vehicle wheel flanges, air compressors, transformers, movable plant machinery, and large pump machinery.

The remaining life assessment of lubricating oil according to this embodiment can be applied to remote monitoring by installing an optical sensor in the lubricating oil inside the machine, and it is also possible to sample the lubricating oil and measure it with an optical sensor outside the machine or in a laboratory. Furthermore, the optical sensor can be replaced by a device that can measure the color coordinates of the lubricating oil.

Central server 240, input device 1001, output device 1002, processing device 1003, storage device 1004, correlation database DB241, antioxidant concentration DB242, chromaticity DB243, data conversion program 244, conversion data 245, diagnostic program

Claims (14)

A diagnostic method for lubricating oil containing an additive used in a machine, comprising:
The first result is a result of measuring the total acid number of the lubricating oil obtained separately in advance,
The second result is the result of measuring the amount of sludge and varnish generated by the lubricating oil, which was obtained separately in advance.
A third result, which is a result of optical measurement of the lubricating oil obtained separately in advance;
Based on
Information indicating a relationship between the first result and the second result;
Information indicating a relationship between the first result and the third result;
and information indicating a relationship between the second result and the third result;
Based on the above information,
First data based on the results of a total acid number measurement of a lubricating oil containing an additive used in the machine;
Second data based on the results of measuring the amount of sludge and varnish generated by lubricating oil containing the additive used in the machine;
and third data based on the result of optical measurement of lubricating oil containing additives used in the machine ,
and converting the third data into an estimate of the total acid number of the lubricant, including the additives, used in the machine using information indicating a relationship between the first result and the third result . The optical measurement includes:
It is characterized by an optical measurement that determines the color coordinate of the lubricating oil from the light transmittance of the lubricating oil.
The method for diagnosing a lubricating oil according to claim 1. As the third result,
The lubricant color coordinate B value or ΔE value is used.
The method for diagnosing a lubricating oil according to claim 1. The measurement of the amount of sludge and varnish generated in the lubricating oil is performed by a contamination measurement method.
The method for diagnosing a lubricating oil according to claim 1. A diagnostic method for lubricating oil containing an additive used in a machine, comprising:
The first result is a result of measuring the total acid number of the lubricating oil obtained separately in advance,
The second result is the result of measuring the amount of sludge and varnish generated by the lubricating oil, which was obtained separately in advance.
A third result, which is a result of optical measurement of the lubricating oil obtained separately in advance;
Based on
Information indicating a relationship between the first result and the second result;
Information indicating a relationship between the first result and the third result;
and information indicating a relationship between the second result and the third result;
Based on the above information,
First data based on the results of a total acid number measurement of a lubricating oil containing an additive used in the machine;
Second data based on the results of measuring the amount of sludge and varnish generated by lubricating oil containing the additive used in the machine;
and third data based on the result of optical measurement of lubricating oil containing additives used in the machine,
The method is characterized in that at least one of the following is performed: setting a first threshold value, which is a threshold value of the total acid number for controlling the amount of sludge/varnish generated, based on information showing the relationship between the first result and the second result; and setting a second threshold value, which is a threshold value of the optical measurement result for controlling the amount of sludge/varnish generated, based on information showing the relationship between the first result and the second result and information showing the relationship between the first result and the third result.
Lubricant diagnostic methods. converting the third data into an estimate of the total acid number of the additive-containing lubricant used in the machine using information indicating the relationship between the first result and the third result;
comparing the estimated value to the first threshold and performing at least one of an indication and a notification based on the comparison result;
The method for diagnosing a lubricating oil according to claim 5. comparing the third data with the second threshold value, and performing at least one of displaying and notifying based on a result of the comparison;
The method for diagnosing a lubricating oil according to claim 5. A diagnostic device for lubricating oil containing additives used in a machine,
A storage device for storing at least one of the first threshold value and the second threshold value according to claim 5,
a sensor for acquiring third data based on the results of optical measurement of a lubricating oil containing additives used in the machine;
The third data is directly or after being converted, and compared with at least one of the first threshold value and the second threshold value, and display or notify based on the comparison result.
Lubricant diagnostic equipment. A diagnostic device for lubricating oil containing additives used in a machine,
a correlation database that records information indicating a relationship between a first result, which is a result of a total acid number measurement of a lubricating oil obtained separately in advance, and a third result, which is a result of an optical measurement obtained separately in advance, based on the first result and the third result;
A data conversion unit that performs conversion between first data based on the result of a total acid number measurement of the lubricating oil containing the additive used in the machine and third data based on the result of an optical measurement of the lubricating oil containing the additive used in the machine based on the information;
Having
The third data is converted into an estimate of the total acid number of the lubricating oil including the additive used in the machine using information indicating the relationship between the first result and the third result.
Lubricant diagnostic equipment. The optical measurement includes:
It is characterized by an optical measurement that determines the color coordinate of the lubricating oil from the light transmittance of the lubricating oil.
The lubricant diagnostic device according to claim 9. As the third result,
The lubricant color coordinate B value or ΔE value is used.
The lubricant diagnostic device according to claim 9. A diagnostic system for lubricating oil containing additives used in a machine, comprising:
An optical sensor for acquiring color information of the lubricant;
A first database storing the total acid number of the lubricating oil;
A data conversion unit that derives the total acid number from the color information;
a correlation database to which the data conversion unit refers,
The correlation database includes:
The information includes information indicating a relationship between a first result, which is a previously obtained total acid number quantitative result, and a third result, which is a color information of the lubricating oil previously obtained by optical measurement;
converting the color information of the lubricant obtained by the optical sensor into an estimated total acid number of the lubricant including the additive used in the machine using information indicating a relationship between the first result and the third result;
Lubricant diagnostic system. The optical sensor includes:
It is characterized by being an optical sensor that determines the color coordinates of lubricants used in machinery by light transmitted through the lubricants.
The lubricant diagnostic system according to claim 12. As the third result,
Characterized by using the color coordinate B value or ΔE value of the lubricating oil.
The lubricant diagnostic system according to claim 12.

Images