Oil deterioration diagnosis device

Abstract

To provide an oil deterioration diagnostic device for accurately and easily detecting deterioration of oil.SOLUTION: A system 10 for replenishing oil flowing in a hydraulic circuit 1 of a work machine with an antioxidant irradiates the oil with measurement light including first and second wave numbers different from each other. A measurement unit 20 that outputs output values ch1 and ch2 corresponding to light intensities of transmitted light from oil, a calculation unit 31 that calculates an output ratio D of an output value ch1 of a first wave number to an output value ch2 of a second wave number, a storage unit 32 in which a first threshold value of an output ratio D of used oil that is oil in which a predetermined amount of antioxidant is consumed is stored in advance, and a determination unit 33 that determines a timing at which a recovery oil is supplied when the output ratio D of the used oil reaches the first threshold value; The first wavenumber is a measured numerical value indicating characteristic infrared absorption in which the transmittance of the oil decreases when the antioxidant contained in the used oil is consumed, and the second wavenumber is a reference numerical value that does not indicate the characteristic infrared absorption even when the antioxidant contained in the used oil is consumed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an oil deterioration diagnosis device for a work machine equipped with a hydraulic circuit. [Background technology]

[0002] Lubricating oils used in construction machinery, vehicles, and other work machines deteriorate over time due to chemical changes, etc. When oil chemically changes, its lubricating properties are lost, and the equipment that makes up the hydraulic circuit may not operate smoothly and may be damaged.

[0003] The main cause of oil chemical deterioration is oxidation. Oil oxidation is accelerated by oxygen, humidity, water, metal ions, and light, but oxygen in the air has the greatest impact on oil oxidation. The oxygen in the air, which contains approximately 21%, reacts with oil to cause oxidation.

[0004] The oxidation reaction of oil occurs through a radical chain reaction (autoxidation). Specifically, peroxides are first produced in the oil. These peroxides are then oxidized to alcohols and ketones, which then become oxides of carboxylic acids, oxyacids, hydroxyacids, and other compounds. These secondary products increase in molecular weight through ester formation and condensation polymerization of oxyacids, turning them into insoluble substances that cause a deterioration in lubricity.

[0005] The oxidation rate of oil is calculated according to the Arrhenius equation as K = Aexp(E / RT) [K: oxidation rate constant, R: gas constant, T: absolute temperature, E: activation energy, A: frequency factor], where the oxidation rate constant K increases exponentially as 1 / T. It is generally said that the reaction rate doubles when the oil temperature rises by 10°C. Furthermore, machinery and equipment that use oil tend to be in high temperatures, creating an environment in which oil oxidation is more likely to progress.

[0006] Patent Document 1 discloses an oil degradation diagnostic device that detects early signs of oil degradation by detecting a decrease in antioxidant, which suppresses oxidation of oil flowing within the hydraulic circuit of a work machine while the work machine is in operation, by focusing on the fact that the numerical value (peak value) at the peak wavelength of the transmittance or absorbance of light transmitted through oil changes as antioxidant is consumed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6869419 Summary of the Invention [Problem to be solved by the invention]

[0008] The device described in Patent Document 1 may have difficulty accurately detecting oil deterioration when the range of fluctuation in transmittance, etc., associated with antioxidant consumption, i.e., the range of fluctuation from the peak value of transmittance, etc., when the oil is new and the peak value of transmittance, etc., when the antioxidant has been consumed to the extent that antioxidant needs to be replenished or the oil changed, is small. Furthermore, because the peak value of transmittance, etc., fluctuates depending on the oil temperature at the time of measurement, there is a problem in that the peak value of transmittance varies with each measurement.

[0009] Therefore, a technical problem arises that must be solved in order to accurately and easily detect oil deterioration, and an object of the present invention is to solve this problem. [Means for solving the problem]

[0010] In order to achieve the above object, the oil deterioration diagnostic device of the present invention is an oil deterioration diagnostic device for a working machine equipped with a hydraulic circuit, and includes a measurement unit that irradiates oil in the hydraulic circuit with measurement light including at least first and second wave numbers that are different from each other, receives transmitted light that has passed through the oil, and outputs output values ​​that are current values ​​or voltage values ​​corresponding to the light intensities of the transmitted light at the first and second wave numbers, a calculation unit that calculates an output ratio that is the ratio of the output value at the first wave number to the output value at the second wave number, and a recovery oil that contains the antioxidant that is replenished to used oil that has oxidized and consumed a predetermined amount of antioxidant. and a determination unit that determines that it is time to replenish the used oil with the recovery oil when the output ratio of the used oil calculated by the calculation unit reaches the first threshold value, wherein the first wavenumber is a numerical value within a measurement region that exhibits characteristic infrared absorption in which the transmittance measured from the transmitted light that has passed through the oil decreases when the antioxidant contained in the used oil is consumed, and the second wavenumber is a numerical value within a reference region that does not exhibit the characteristic infrared absorption even when the antioxidant contained in the used oil is consumed.

[0011] In order to achieve the above object, the oil deterioration diagnostic device of the present invention is an oil deterioration diagnostic device for a working machine equipped with a hydraulic circuit, and includes a measurement unit that irradiates oil in the hydraulic circuit with measurement light including at least first and second wave numbers that are different from each other, receives the transmitted light that has passed through the oil, and outputs output values ​​that are current values ​​or voltage values ​​corresponding to the light intensity of the transmitted light at the first and second wave numbers, a calculation unit that calculates an output ratio that is the ratio of the output value at the first wave number to the output value at the second wave number, and ... used oil that contains a predetermined amount of oxides generated by oxidation to new oil. The oil measuring device is provided with a memory unit in which a second threshold value for the output ratio of the used oil when changing to a certain new oil is stored in advance, and a judgment unit that judges that the time has come to change the used oil to the new oil when the output ratio of the used oil calculated by the calculation unit reaches the second threshold value, wherein the first wave number is a numerical value within a measurement region that exhibits characteristic infrared absorption in which the transmittance measured from the transmitted light that has passed through the oil decreases when the oxide is generated in the used oil, and the second wave number is a numerical value within a reference region that does not exhibit the characteristic infrared absorption even when the oxide is generated in the used oil. [Effects of the Invention]

[0012] The present invention can accurately and easily detect oil deterioration. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing the configuration of a work machine to which an antioxidant replenishment system according to a first embodiment of the present invention is applied. [Figure 2] A schematic diagram showing the process of autoxidation of oil. [Figure 3] 1 is a graph showing an infrared absorption spectrum illustrating the change in wave number and transmittance over time for an oil. [Figure 4] This is an enlarged graph of Figure 3 around the wavenumber range of 3000 to 4000 cm-1. [Figure 5] This is an enlarged graph of Figure 3, showing the wavenumber range of 1500 to 2000 cm-1. [Figure 6] 4 is a flowchart showing a procedure for diagnosing oil deterioration. [Figure 7] Graph showing the correlation between the absorbance of oil at a wavenumber of 1740 cm-1 and the power ratio D. [Figure 8] FIG. 1 is a schematic diagram showing the configuration of a work machine to which an antioxidant replenishment system according to a first modified example of the present invention is applied. [Figure 9] FIG. 10 is a schematic diagram showing the configuration of a work machine to which an antioxidant replenishment system according to a second modified example of the present invention is applied. [Figure 10] FIG. 5 is a schematic diagram showing the configuration of a work machine to which an antioxidant replenishment system according to a second embodiment of the present invention is applied. [Figure 11] FIG. 10 is a perspective view showing the configuration of an oil cell according to a second modified example of the present invention. [Figure 12] 12 is a schematic diagram showing the positional relationship between the oil cell shown in FIG. 11 and the light projector and light receiver. DETAILED DESCRIPTION OF THE INVENTION

[0014] Each embodiment of the present invention will be described with reference to the drawings. Note that, hereinafter, when referring to the number, numerical value, amount, range, etc. of components, unless otherwise specified or when it is clearly limited to a specific number in principle, it is not limited to the specific number, and may be more or less than the specific number.

[0015] Furthermore, when referring to the shape or positional relationship of components, etc., it includes things that are substantially similar or approximate to those shapes, etc., unless otherwise specified or when it is clearly considered otherwise in principle.

[0016] In addition, the drawings may exaggerate characteristic parts to make the features easier to understand, and the dimensional proportions of the components may not be the same as in reality. In addition, in cross-sectional views, hatching of some components may be omitted to make the cross-sectional structure of the components easier to understand.

[0017] First Embodiment FIG. 1 is a schematic diagram showing the configuration of a hydraulically driven construction machine to which an oil deterioration diagnosis device 10 according to a first embodiment of the present invention is applied. The construction machine includes a hydraulic circuit 1 as a power source. The hydraulic circuit 1 includes an oil tank 2, a hydraulic pump 3, a directional control valve 4, and an actuator 5. Oil stored in the oil tank 2 is pressurized by the hydraulic pump 3 and supplied to a predetermined actuator 5 via the directional control valve 4. The actuator 5 is connected to a power source (motor, cylinder, etc.) not shown. The oil returning from the actuator 5 returns to the oil tank 2 via the directional control valve 4. The operation of the various components of the hydraulic circuit 1 is controlled by a controller not shown. The oil is prepared by adding an antioxidant to a base oil, and the amount of antioxidant added is set to, for example, 0.7 wt%. The antioxidant contained in the oil is, for example, a phenolic antioxidant or zinc dialkyldithiophosphate.

[0018] The oil deterioration diagnosis device 10 includes a measurement unit 20, a diagnosis unit 30, and a replenishment unit 40. The oil deterioration diagnosis device 10 diagnoses the deterioration state of the oil flowing within the hydraulic circuit 1 in-line, that is, without draining the oil from the hydraulic circuit 1, while the hydraulic circuit 1 is in operation. In-line diagnosis is ideal for medium- to large-sized hydraulic excavators, for example, and is particularly suitable for unmanned large equipment.

[0019] <Measurement part> The measurement unit 20 is an infrared sensor that includes a pair of light-projecting devices 21a, 21b and a pair of light-receiving devices 22a, 22b that are arranged opposite the light-projecting devices 21a, 21b across the pipeline 6 that connects various devices in the hydraulic circuit 1.

[0020] The light projectors 21a and 21b each include a laser diode as a light source. Each laser diode continuously or intermittently emits measurement light set to a predetermined wave number. Each laser diode irradiates the measurement light toward the oil flowing through the pipe 6 upstream of the oil tank 2. A portion of the pipe 6 is formed to be transparent so that the measurement light can pass through. The light projectors 21a and 21b may be arranged to irradiate the measurement light toward the oil in the oil tank 2.

[0021] Each of the light receivers 22a and 22b includes a photodiode as a light receiving element and an amplifier that amplifies the signal output by the photodiode. The photodiode receives measurement light (transmitted light) that has passed through the pipe 6. The detection wave number of the photodiode of the light receiver 22a is set corresponding to the wave number of the measurement light emitted by the laser diode of the light projector 21a, and the detection wave number of the photodiode of the light receiver 22b is set corresponding to the wave number of the measurement light emitted by the laser diode of the light projector 21b. The light receivers 22a and 22b each output an output value, which is a current value or a voltage value corresponding to the light intensity of the received transmitted light, to the diagnostic unit 30.

[0022] Here, the wavenumber of the measurement light (transmitted light) emitted by the light-projector 21a and received by the light-receiver 22a is set to a value within a measurement range that exhibits characteristic infrared absorption, where the transmittance measured from the transmitted light that has passed through the oil decreases or the absorbance increases when the antioxidant contained in the oil is consumed. Hereinafter, the wavenumber of the transmitted light emitted by the light-projector 21a and received by the light-receiver 22a is referred to as the "first wavenumber." Furthermore, the wavenumber of the measurement light (transmitted light) emitted by the light-projector 21b and received by the light-receiver 22b is set to a value within a reference range in which the decrease in transmittance or the increase in absorbance is relatively small, even when the antioxidant contained in the oil is consumed, i.e., the characteristic infrared absorption described above is not exhibited. Hereinafter, the wavenumber of the transmitted light emitted by the light-projector 21b and received by the light-receiver 22b is referred to as the "second wavenumber." Furthermore, since transmittance, which is the ratio of measured light intensity to transmitted light intensity, and absorbance, which is calculated from measured light intensity and transmitted light intensity based on Lambert-Beer's law, are correlated with each other, either may be used, but the following explanation will use transmittance as an example.

[0023] <Diagnostics Department> The diagnosis unit 30 includes a calculation unit 31, a storage unit 32, a determination unit 33, and a notification unit .

[0024] The calculation unit 31 calculates an output ratio D, which is the ratio (ch1 / ch2) of the output value ch1 at the first wave number output by the photoreceiver 22a to the output value ch2 at the second wave number output by the photoreceiver 22b, and transmits the calculated output ratio to the judgment unit 33.

[0025] The memory unit 32 pre-stores a first threshold value which is the output ratio of the used oil when oil (used oil) that has been oxidatively deteriorated and has consumed its antioxidants is replenished with recovery oil containing antioxidants, and a second threshold value which is the output ratio of the used oil when the used oil is replaced with new oil (new oil).

[0026] The determination unit 33 retrieves a first threshold value from the memory unit 32, and compares the output ratio of the used oil calculated by the calculation unit 31 with the first threshold value to determine whether it is time to replenish the used oil with recovery oil. The determination unit 33 also retrieves a second threshold value from the memory unit 32, and compares the output ratio of the used oil calculated by the calculation unit 31 with the second threshold value to determine whether it is time to change the used oil to new oil. Furthermore, when the determination unit 33 determines that it is time to replenish the used oil with recovery oil or to change the used oil to new oil, the notification unit 34 notifies the operator of this by sound, light, or the like.

[0027] <Supplementary section> The refilling unit 40 includes a refilling tank 41 and a refilling pump 42 .

[0028] The refill tank 41 stores recovery oil. The capacity of the recovery oil stored in the refill tank 41 is preferably set to an amount that allows repeated replenishment of recovery oil without the need for additional oil addition. The recovery oil is prepared by dissolving a solid antioxidant at room temperature and adding it to the base oil, with the amount of antioxidant added being set to, for example, 10 wt%. The refill tank 41 may be provided with a heater 41a that keeps the recovery oil at a temperature above the melting point of the antioxidant (for example, 70°C) to prevent the antioxidant contained in the recovery oil from solidifying.

[0029] The replenishment pump 42 is, for example, a metering pump, and supplies the recovery oil stored in the replenishment tank 41 to the used oil in the oil tank 2. The amount of recovery oil discharged by the replenishment pump 42 is arbitrarily controlled by the pump control unit 43.

[0030] Next, the operation of the oil deterioration diagnostic device 10 will be described.

[0031] First, let us explain the oxidation reaction of oil. Figure 2 shows the oil usage time on the horizontal axis and the amount of products produced in the oil on the vertical axis. As shown in Figure 2, the amount of products produced in the oil changes over time depending on the degree of oil deterioration. Oil flowing through the hydraulic circuit 1 tends to reach high temperatures, making oxidation reactions more likely to occur. This oxidation reaction is caused by a radical chain reaction (autoxidation reaction), and first, peroxides in the oil increase exponentially (peroxide generation period). The peroxides are then oxidized to alcohols and ketones, which then become oxides such as carboxylic acids, hydroxy acids, and hydroxy acids (oxide generation period). These secondary products increase in molecular weight through ester formation and condensation polymerization of hydroxy acids, becoming insoluble substances, which increases the viscosity of the oil and reduces its lubricity (viscosity increase period).

[0032] In addition, new oil contains antioxidants that react with free radicals to suppress radical chain reactions, but as the oxidation reaction progresses, the antioxidants are consumed and reduced, after which peroxides are produced (induction period).

[0033] Next, Figure 3 is a graph showing infrared absorption spectra of oil containing a phenolic antioxidant, showing how its transmittance in the wavenumber range of 500 to 4000 cm-1 changes with the oxidation reaction of the oil. Figure 4 is an enlarged view of the wavenumber range of 3000 to 4000 cm-1 in Figure 3. Figure 5 is an enlarged view of the wavenumber range of 1500 to 2000 cm-1 in Figure 3. The infrared absorption spectra shown in Figures 3 to 5 were measured using a spectrophotometer (FTIR). The solid lines in Figures 3 to 5 represent new oil in a state where no oxidation has occurred, the thin dashed lines represent used oil in a state where oxidation degradation has progressed and antioxidant replenishment is required (middle of the induction period), and the thick chain lines represent used oil in a state where oxidation degradation has progressed further and oil replacement is required (early viscosity increase period).

[0034] As the oil undergoes oxidative degradation, the transmitted light decreases and the absorbance increases. Figures 3 and 4 show that the transmittance decreases as the oil undergoes oxidative degradation in the wavenumber range of 3000 to 3500 cm-1. This is due to the infrared absorption of the C-H stretching vibration.

[0035] Furthermore, Figures 3 and 5 show that transmittance decreases near wavenumbers of 1500 cm-1 and 1700 cm-1 as the oil's oxidation degradation progresses. The decrease in transmittance near wavenumber 1500 cm-1 is due to infrared absorption of C=O bending vibrations. The decrease in transmittance near wavenumber 1700 cm-1 is due to infrared absorption of C=O.

[0036] As shown above, the measurement ranges of wavenumbers around 3000 to 3500 cm-1, 1500 cm-1, and 1700 cm-1 show characteristic infrared absorptions that indicate a decrease in transmittance due to oxidative deterioration of the oil. On the other hand, in the reference range of wavenumbers around 2000 to 2500 cm-1, it can be seen that the decrease in transmittance due to oil deterioration is relatively small.

[0037] The diagnostic unit 30 determines, using the procedure shown in Figure 6, whether it is time to replenish used oil, whose antioxidant content has decreased due to such oxidative deterioration, with recovery oil or to replace the used oil with new oil.

[0038] First, while the construction machine is in operation, projectors 21a and 21b emit measurement light at predetermined intervals (for example, one second), and receivers 22a and 22b receive the transmitted light that has passed through the oil flowing inside pipeline 6. Receiver 22a outputs an output value ch1 at a first wavenumber, and receiver 22b outputs an output value ch2 at a second wavenumber (step S1). The wavenumbers of the measurement light emitted by projectors 21a and 21b exhibit a normal distribution having an arbitrary half-width, and the first wavenumber, which is the median of the wavenumbers of the measurement light emitted by projector 21a, is set to 3200 cm-1 within the measurement region, and the second wavenumber, which is the median of the wavenumbers of the measurement light emitted by projector 21b, is set to 2000 cm-1 within the reference region.

[0039] Next, the calculation unit 31 calculates an output ratio D of the output value ch1 at the first wave number output by the light receiver 22a to the output value ch2 at the second wave number output by the light receiver 22b (step S2). The output ratio D calculated by the calculation unit 31 represents the degree of deterioration of the oil used.

[0040] Here, the output ratio D is the ratio of the output value ch1, which indicates the characteristic infrared absorption associated with oxidative degradation of oil, to the output value ch2, which indicates the small characteristic infrared absorption. Therefore, variations in the transmittance peak value (temperature error) due to fluctuations in oil temperature are canceled out. Furthermore, compared to conventional methods of detecting the degree of oil degradation based on a single peak value (absolute value) of transmittance, the output ratio D exhibits more pronounced fluctuations due to oil degradation, allowing for more accurate assessment of the degree of oil degradation. Furthermore, while a change in the type of antioxidant contained in the oil required tedious fine-tuning of the peak wavelength in conventional methods, the output ratio D is easy to use because it represents the degree of deterioration of the oil used regardless of the type of antioxidant contained in the oil. The calculation unit 31 preferably stores the calculated output ratios D in the memory unit 32 in chronological order to facilitate comparisons over the duration of oil use.

[0041] Next, the determination unit 33 determines the time to replenish the used oil with recovery oil. Specifically, the determination unit 33 retrieves a first threshold value from the storage unit 32 and determines whether the output ratio D for the used oil calculated by the calculation unit 31 is equal to or greater than the first threshold value (step S3).

[0042] Figure 7 is a graph showing the relationship between the output ratio D and the absorbance of oil containing oxides. Figure 7 shows that, assuming the output ratio D of new oil is 1, as the oxidative degradation of used oil progresses, the output ratio D decreases and the absorbance increases. Therefore, a first threshold value is set to the output ratio D corresponding to the used oil when it is time to replenish recovery oil (corresponding to the middle of the induction period in Figure 2), and a second threshold value is set to the output ratio D corresponding to the used oil when it is time to change to new oil (corresponding to the viscosity increase period in Figure 2). By monitoring the magnitude relationship between the output ratio D and the first and second threshold values, it is possible to determine whether the deterioration of the used oil is such that it requires replenishment of recovery oil or replacement with new oil. Note that Figure 7 illustrates an example of a first threshold value of 0.8 and a second threshold value of 0.3, but these values ​​are not limited to these.

[0043] For example, when the output ratio D is equal to or greater than the first threshold value (Yes in step S3), as shown at point a in Figure 7, the used oil contains a sufficient amount of antioxidant, and the judgment unit 33 judges that it is not yet time to replenish the used oil with recovery oil, and returns to step S1.

[0044] On the other hand, when the output ratio D falls below the first threshold (No in step S3), as shown by point b in Fig. 7, the determination unit 33 determines that the antioxidant contained in the used oil has been consumed and that it is time to replenish the used oil with recovery oil, and notifies the operator via the notification unit 34 that it is time to replenish the used oil with recovery oil (step S4). Next, the replenishment unit 40 supplies the recovery oil stored in the replenishment tank 41 to the used oil in the oil tank 2 (step S5). As the recovery oil is replenished to the used oil, the antioxidant contained in the used oil increases, and the output ratio D shifts from point b to the upper left on the graph in Fig. 7.

[0045] After the replenishing unit 40 replenishes the used oil with the recovery oil, the light-projectors 21a and 21b irradiate the oil in the pipeline 6 with measurement light, the light-receivers 22a and 22b receive the transmitted light that has passed through the oil in the pipeline 6, the light-receiver 22a outputs an output value ch1 at the first wave number, and the light-receiver 22b outputs an output value ch2 at the second wave number (step S6). Subsequently, the calculation unit 31 calculates the output ratio D of the used oil after replenishment (step S7).

[0046] Next, the determination unit 33 retrieves the first threshold value from the storage unit 32, and determines whether the output ratio D of the used oil after replenishment calculated by the calculation unit 31 is equal to or greater than the first threshold value (step S8).

[0047] For example, as shown at point c in Figure 7, if the output ratio D of the used oil after replenishment returns to above the first threshold value (Yes in step S8), the deterioration state of the used oil corresponds to the early stage of the induction period shown in Figure 2, and the judgment unit 33 determines that the time has not yet come to replenish the used oil with recovery oil, and returns to step S1.

[0048] On the other hand, if the output ratio D of the used oil after replenishment falls below the first threshold value (No in step S8), as in the state shown at point d in Fig. 7, the determination unit 33 proceeds to determine the timing of changing the used oil to new oil. Specifically, the determination unit 33 retrieves the second threshold value from the storage unit 32 and determines whether the output ratio D of the used oil calculated by the calculation unit 31 is equal to or greater than the second threshold value (step S9).

[0049] For example, when the output ratio D is equal to or greater than the second threshold value (Yes in step S9), as shown at point e in Figure 7, the deterioration state of the used oil corresponds to either the middle of the induction period, the peroxide production period, or the oxide production period shown in Figure 2. At this time, the determination unit 33 determines that it is not yet time to replace the used oil with new oil, and the oil deterioration diagnosis device 10 continues measuring the deterioration level of the used oil. That is, the photodetectors 22a and 22b output the output values ​​ch1 and ch2 (step S10), the calculation unit 31 calculates the output ratio D of the used oil (step S11), and the process returns to step S9.

[0050] On the other hand, when the output ratio D is below the second threshold, as shown at point f in Figure 7, the deterioration of the used oil corresponds to the viscosity increase period shown in Figure 2. At this time, the determination unit 33 notifies the operator via the notification unit 34 that it is time to change the used oil for new oil (step S12). When the operator receives the notification from the notification unit 34 that it is time to change the oil, the oil in the hydraulic circuit 1 is changed for new oil (step S13).

[0051] In this way, the oil deterioration diagnosis device 10 according to this embodiment is an oil deterioration diagnosis device 10 for a working machine equipped with a hydraulic circuit 1, and includes a measurement unit 20 that irradiates oil in the hydraulic circuit 1 with measurement light including at least first and second wave numbers that are different from each other, receives the transmitted light that has passed through the oil, and outputs output values ​​ch1 and ch2 that are current values ​​or voltage values ​​corresponding to the light intensity of the transmitted light at the first and second wave numbers, a calculation unit 31 that calculates an output ratio D that is the ratio of the output value ch1 at the first wave number to the output value ch2 at the second wave number, and a calculation unit 32 that calculates an antioxidant for used oil that has been oxidized and has consumed a predetermined amount of antioxidant. The apparatus includes a memory unit (32) in which a first threshold value of the output ratio D of the oil used when replenishing recovery oil containing an antioxidant is stored in advance, and a judgment unit (33) that judges that the time has come to replenishing the used oil with recovery oil when the output ratio D of the oil used calculated by the calculation unit (31) reaches the first threshold value, wherein the first wavenumber is a numerical value within a measurement region that exhibits characteristic infrared absorption where the transmittance measured from transmitted light through the oil decreases when the antioxidant contained in the used oil is consumed, and the second wavenumber is a numerical value within a reference region that does not exhibit characteristic infrared absorption even when the antioxidant contained in the used oil is consumed.

[0052] With this configuration, when the output ratio D, which clearly indicates the degree of oil deterioration after excluding temperature errors, reaches the first threshold value, the determination unit 33 determines that it is time to replenish the used oil with recovery oil, thereby making it possible to accurately and easily detect the degree of oil deterioration in the hydraulic circuit 1. Furthermore, since recovery oil can be replenished to the used oil in a timely manner, the frequency of oil replenishment in the hydraulic circuit 1 can be reduced.

[0053] The oil deterioration diagnosis device 10 according to this embodiment is an oil deterioration diagnosis device 10 for a working machine equipped with a hydraulic circuit 1, and includes a measurement unit 20 that irradiates oil in the hydraulic circuit 1 with measurement light including at least first and second wave numbers that are different from each other, receives the transmitted light that has passed through the oil, and outputs output values ​​ch1 and ch2 that are current values ​​or voltage values ​​corresponding to the light intensities of the transmitted light at the first and second wave numbers, a calculation unit 31 that calculates an output ratio D that is the ratio of the output value ch1 at the first wave number to the output value ch2 at the second wave number, and a used oil that is oil that contains a predetermined amount of oxides generated by oxidation. The apparatus is equipped with a memory unit 32 in which a second threshold value of the output ratio D of the used oil when the used oil is replaced with new oil, which is a brand new oil, is stored in advance, and a judgment unit 33 that judges that it is time to replace the used oil with new oil when the output ratio D of the used oil calculated by the calculation unit 31 reaches the second threshold value, wherein the first wave number is a numerical value within a measurement region that shows characteristic infrared absorption in which the transmittance measured from transmitted light that has passed through the oil decreases when oxides are generated in the used oil, and the second wave number is a numerical value within a reference region that does not show characteristic infrared absorption even when oxides are generated in the used oil.

[0054] With this configuration, when the output ratio D, which clearly indicates the degree of oil deterioration after eliminating temperature errors, reaches the second threshold value, the determination unit 33 determines that it is time to change the used oil for new oil, thereby making it possible to accurately and easily detect the degree of oil deterioration in the hydraulic circuit 1. Furthermore, since the used oil can be changed for new oil in a timely manner, the frequency of oil changes in the hydraulic circuit 1 can be reduced.

[0055] <First Modification of First Embodiment> Next, an oil degradation diagnosis device 50 according to a first modified example of the above-described embodiment will be described with reference to Fig. 8. The oil degradation diagnosis device 50 according to this modified example differs from the oil degradation diagnosis device 10 according to the above-described first embodiment only in the configuration described below, and the other configurations are the same. Therefore, the common configurations are assigned the same reference numerals and redundant explanations will be omitted.

[0056] In this modification, oil in the oil tank 2 is circulated through a dummy conduit 7 branching off from the conduit 6. Reference numeral 8 in FIG. 8 denotes a hydraulic pump that sucks oil from the oil tank 2 and supplies it to the dummy conduit 7. A portion of the dummy conduit 7 is formed to be transparent so that measurement light can pass through. The measurement unit 20 includes a pair of light-emitters 21a, 21b provided on one side of the dummy conduit 7, and a pair of light-receivers 22a, 22b provided opposite the pair of light-emitters 21a, 21b across the dummy conduit 7. The light-receiver 22a outputs an output value ch1 at a first wave number, and the light-receiver 22b outputs an output value ch2 at a second wave number.

[0057] The calculation unit 31 calculates the output ratio D based on the output values ​​ch1 and ch2 output by the photodetectors 22a and 22b, respectively, and the judgment unit 33 calls up the first threshold value and the second threshold value from the memory unit 32 in accordance with the procedure shown in Figure 6, and judges whether the time has come to replenish the used oil in the hydraulic circuit 1 with recovery oil or whether the time has come to replace the used oil in the hydraulic circuit 1 with new oil, based on the output ratio D, which is the degree of deterioration of the used oil in the dummy pipeline 7.

[0058] In this way, the oil deterioration diagnostic device 50 diagnoses the deterioration of the oil flowing in the hydraulic circuit 1 online, that is, by flowing the oil through the dummy pipe 7 branching off from the hydraulic circuit 1 while the hydraulic circuit 1 is in operation.

[0059] <Second Modification of First Embodiment> Next, an oil degradation diagnosis device 60 according to a second modified example of the above-described embodiment will be described with reference to Fig. 9. The oil degradation diagnosis device 60 according to this modified example differs from the oil degradation diagnosis device 10 according to the above-described embodiment only in the configuration described below, and the other configurations are the same. Therefore, the common configurations are assigned the same reference numerals and redundant explanations will be omitted.

[0060] The measurement unit 20 is an infrared sensor that includes a light source, a projector 21c, and a pair of light receivers 22c that are arranged opposite the projector 21c across the pipeline 6 that connects various devices in the hydraulic circuit 1.

[0061] The projector 21c is, for example, a thermal infrared light source. The projector 21c generally uses tungsten, tantalum, molybdenum, or nichrome for the filament, and continuously or intermittently emits a spectrum (measurement light) that approximates blackbody radiation. The projector 21c irradiates the measurement light toward the oil flowing through the pipe 6 upstream of the oil tank 2.

[0062] The light receiver 22c includes a pyroelectric sensor as a light receiving element and an amplifier that amplifies the signal output by the pyroelectric sensor. The pyroelectric sensor is composed of two pyroelectric elements 22d and 22e, and optical bandpass filters 22f and 22g are attached to the pyroelectric elements 22d and 22e, respectively. When the pyroelectric elements 22d and 22e of the pyroelectric sensor receive measurement light (transmitted light) that has passed through the pipe 6 and the bandpass filters 22f and 22g, they output an output value, which is a current value or a voltage value corresponding to the intensity of the transmitted light, to the calculation unit 31 in accordance with the movement of electrons caused by slight changes in the surface temperature.

[0063] The wavenumbers of the transmitted light passing through the optical bandpass filters 22f and 22g exhibit a normal distribution with an arbitrary half-width. The detected wavenumber (first wavenumber) of the optical bandpass filter 22f, which is the median value of the wavenumbers of the transmitted light passing through the optical bandpass filter 22f, is set to a value within a measurement region exhibiting characteristic infrared absorption, for example, 3200 cm-1. The detected wavenumber (second wavenumber) of the optical bandpass filter 22g, which is the median value of the wavenumbers of the transmitted light passing through the optical bandpass filter 22g, is set to a value within a reference region not exhibiting characteristic infrared absorption, for example, 2000 cm-1. The number of pyroelectric elements and optical bandpass filters in the pyroelectric sensor may be three or more.

[0064] The calculation unit 31 calculates an output ratio D, which is the ratio (ch3 / ch4) of the output value ch3 at the first wave number output by the pyroelectric element 22d to the output value ch4 at the second wave number output by the pyroelectric element 22e, and transmits the calculated output ratio D to the judgment unit 33.

[0065] The determination unit 33 calls up the first threshold value and the second threshold value from the memory unit 32 according to the procedure shown in FIG. 6, and compares the output ratio D of the used oil calculated by the calculation unit 31 with the first and second threshold values, and determines whether or not the time has come to replenish the used oil in the hydraulic circuit 1 with recovery oil or whether or not the time has come to replace the used oil in the hydraulic circuit 1 with new oil, based on the output ratio D, which is the degree of deterioration of the used oil in the pipeline 6.

[0066] <Second embodiment> Next, an oil degradation diagnosis device 70 according to a second embodiment of the present invention will be described with reference to Fig. 10. The oil degradation diagnosis device 70 according to this embodiment differs from the oil degradation diagnosis device 10 according to the first embodiment described above only in the configuration described below, and the other configurations are the same. Therefore, the common configurations are assigned the same reference numerals and redundant explanations will be omitted.

[0067] The oil deterioration diagnosis device 70 according to this embodiment diagnoses, offline, the degree of deterioration of oil extracted from the oil tank 2. Offline diagnosis is suitable for, for example, a small hydraulic excavator or the like that does not require inline measurement but does require simple oil deterioration measurement.

[0068] The oil deterioration diagnostic device 70 includes an oil cell 80 and a holding case 90 inside which the oil cell 80 can be detachably attached.

[0069] The oil cell 80 is made of brass and can contain oil drained from the oil tank 2. The oil volume that the oil cell 80 can contain is set to, for example, several ml. Transparent observation windows (transmission windows) 82 that are capable of transmitting light are provided on the side surfaces 81a and 81b of the holding case 90 that face the pair of sensor holding surfaces 91a and 91b, respectively. As shown in FIGS. 3 to 5, the observation window 82 is made of a material that exhibits high transmittance in the infrared range of 500 to 4000 cm-1, preferably a material that exhibits high transmittance in the range of 1700 to 4000 cm-1, where absorption due to oil degradation occurs. The observation window 82 can be made of, for example, sapphire, CaF2, Ge, Si, BaF2, ZnSe, ZnS, etc.

[0070] The holding case 90 can accommodate the oil cell 80 in a gap 92 between a pair of sensor holding surfaces 91a, 91b. A light projector 21c is provided on the sensor holding surface 91a, and a light receiver 22c is provided on the sensor holding surface 91b in a position facing the light projector 21c. Measurement light emitted from the light projector 21c passes through an observation window 82 and is absorbed by the oil at a characteristic wavenumber. The measurement light then passes through the observation window 82 and enters the light receiver 22c. The light projector 21c and the light receiver 22c are the same as those described in the second modified example. The distance between the light projector 21c and the light receiver 22c is set to approximately 1 mm. The holding case 90 is formed into a box shape that opens upward and is made up of sensor holding surfaces 91a, 91b, side surfaces 93a, 93b, and a bottom surface (not shown).

[0071] Next, a procedure for diagnosing whether or not it is time to replenish the oil with recovery oil or to replace the oil with new oil using the oil deterioration diagnosis device 70 according to this embodiment will be described.

[0072] First, the operator transfers the oil in the oil tank 2 into the oil cell 80 using, for example, a pipette Pi.

[0073] Next, the light projector 21c irradiates the measurement light at predetermined intervals (for example, every second), and the pyroelectric elements 22d and 22e receive the transmitted light that has passed through the oil cell 80 and the optical bandpass filters 22f and 22g.

[0074] Next, the calculation unit 31 calculates an output ratio D, which is the ratio (ch3 / ch4) of the output value ch3 at the first wave number output by the pyroelectric element 22d to the output value ch4 at the second wave number output by the pyroelectric element 22e, and transmits the calculated output ratio D to the judgment unit 33.

[0075] Next, the determination unit 33 calls up the first threshold value from the storage unit 32 in accordance with the procedure shown in FIG. 6, and determines whether the output ratio D for the oil used calculated by the calculation unit 31 is equal to or greater than the first threshold value.

[0076] When the output ratio D falls below the first threshold value, the determination unit 33 determines that the antioxidant contained in the used oil has been consumed and that it is time to replenish the used oil with recovery oil, and notifies the operator via the notification unit 34 that it is time to replenish the used oil with recovery oil, and the replenishment unit 40 replenishes the used oil with recovery oil. Note that the operator who has received the notification from the notification unit 34 that it is time to replenish recovery oil may manually replenish the recovery oil.

[0077] When the used oil is replenished with recovery oil, the replenished used oil is transferred from the oil tank 2 to the oil cell 80, and then the calculation unit 31 calculates the output ratio D based on the output values ​​ch3 and ch4 output by the photodetector 22c, and the judgment unit 33 calculates the output ratio D for the used oil replenished with recovery oil.

[0078] In addition, if the output ratio D of the oil used after replenishment is below the first threshold value, the judgment unit 33 calls up the second threshold value from the memory unit 32 and determines whether the output ratio D of the oil used after replenishment calculated by the calculation unit 31 is equal to or greater than the second threshold value.

[0079] If the output ratio D is below the second threshold value, the determination unit 33 determines that the oil is undergoing oxidation degradation and notifies the operator via the notification unit 34 that it is time to change the used oil for new oil. When the operator receives the notification from the notification unit 34 that it is time to change the oil, the oil in the hydraulic circuit 1 is changed for new oil.

[0080] <Modification of the second embodiment> Next, a modified example of the second embodiment of the present invention will be described. This modified example has a common configuration with the oil deterioration diagnosis device 70 according to the second embodiment described above, except for the configuration of the oil cell 80. Therefore, the common configuration will be assigned the same reference numerals and redundant explanations will be omitted.

[0081] In order to increase the output value of the transmitted light output by the photoreceiver 22c, it is possible to reduce the absorption of the measurement light at the observation window 82 or to increase the output of the projector 21c to increase the intensity of the measurement light, but the former is easier to ensure the output value of the transmitted light. In other words, if the transmittance of the observation window 82 is increased, the output value of the photoreceiver 22c can also be increased.

[0082] Although sapphire and the like mentioned above as materials for the observation window 82 exhibit excellent transmittance, they are expensive, and even if the oil cell 80 is mass-produced by resin injection molding in order to reduce the procurement cost of the oil cell 80, if the observation window 82 made of an expensive material such as sapphire is fixed to the oil cell 80 with an adhesive, an increase in the procurement cost of the oil cell 80 is unavoidable. Therefore, in this modified example, we considered replacing the observation window 82 made of an expensive material with a resin film that exhibits excellent transmittance.

[0083] Similar to oil, resins have the optical property of having a material-specific absorption region in the infrared region. Therefore, the optical selection conditions for the resin film include ensuring that the absorption region of the resin film does not overlap with the absorption region specific to oil, and reducing the thickness of the resin film to reduce the amount of absorbed measurement light.

[0084] Chemical selection criteria for resin films include resistance to oil and solvents used in cleaning. Materials that are chemically resistant to mineral oil include vinylidene chloride, acrylonitrile butadiene styrene (ABS), polyamide resin, fluororesin (PFA), polycarbonate (PC), phenolic resin, melamine resin, and furan resin. Furthermore, among these materials that are chemically resistant to mineral oil, nylon, fluororesin, PC, phenolic resin, melamine resin, and furan resin are also resistant to hexane, a solvent used in oil cleaning.

[0085] In the following, comparative experiments were conducted using PC and PFA, film materials that are resistant to mineral oil and hexane. If the output ratio D (ch3 / ch4) when using a sapphire observation window 82 was 100, the output ratio D when using a 0.05 mm thick PC film was 99, and the output ratio D when using a 0.1 mm thick PFA film was 91. In this way, it was confirmed that the sapphire observation window 82 can be replaced with a 0.05 mm thick PC film or a 0.1 mm thick PFA film. The thicknesses of the PC film and PFA film are not limited to these, and can be changed as long as the required transmittance is maintained.

[0086] The structure of an oil cell 80 using such a resin film is shown in Fig. 11. The oil cell 80 shown in Fig. 11 includes an oil cell main body 83, an oil storage section 84, and a PC film or PFA film as a transmission window 85.

[0087] The oil cell body 83 is formed by resin injection molding. The resin that forms the oil cell body 83 may be any resin as long as the parts that may come into contact with oil are resistant to oil.

[0088] The oil storage section 84 is bored out in a substantially circular shape from one side surface 83a to the other side surface 83b near the center of the oil cell main body 83, and is formed with openings on both side surfaces 83a, 83b and the top surface 83c of the oil cell main body 83. The oil storage section 84 may have any shape.

[0089] The transmission window 85 is attached to the oil cell main body 83 so as to close the openings 84a and 84b of the oil storage section 84, which open to both side surfaces 83a and 83b. As shown in Fig. 12, oil is stored in the area surrounded by the openings 84a and 84b of the oil storage section 84 and the two transmission windows 85.

[0090] The oil cell 80 produced in this manner can be disposable due to reduced procurement costs, and can eliminate the effort of cleaning and variations in cleanliness, allowing the degree of deterioration of the oil used to be obtained with high reproducibility.

[0091] Next, a manufacturing procedure for the oil cell 80, which is made up of the oil cell body 83, which is a resin injection molded product, and a resin film as the transmission window 85, will be described.

[0092] In the first manufacturing procedure, the oil cell 80 is produced by injection molding the oil cell body 83 with PC resin, and simultaneously molding a 0.05 mm thick PC film as the transmission window 85 by film insert molding.

[0093] Specifically, first, a PC film is placed in a mold and heated and softened with a heater. Next, the PC film is pressed against the mold using vacuum, compressed air, etc., and formed to the shape of the mold, after which excess PC film is trimmed to obtain the transmission window 85. Next, the trimmed transmission window 85 is inserted into the molding mold, and after the mold is closed, the interior is filled with PC resin. After cooling, the mold is removed and the oil cell 80 is taken out.

[0094] According to this manufacturing procedure, the oil cell body 83 and the transmission window 85 are both made of PC, which has excellent compatibility and good bonding properties, and the oil cell 80 in which the sapphire observation window 82 is replaced with a transmission window 85 made of PC film can be manufactured inexpensively.

[0095] Next, in the second manufacturing procedure, similar to the oil cell shown in Figure 11, a 0.1 mm thick PFA film (transmission window 85) cut to a 50 mm square size is electrostatically attached to both side surfaces 83a, 83b of a 1 mm thick nylon oil cell body 83 to produce an oil cell 80.

[0096] According to the known triboelectric series, fluororesins such as PFA have higher insulating properties than other materials and are on the most negative side, becoming negatively charged at a high potential when they come into contact with, rub against, or peel off from other materials. On the other hand, glass and nylon tend to become positively charged and adhere to fluororesins with strong electrostatic forces. Therefore, this manufacturing procedure allows for the use of this strong electrostatic force to produce a simple oil cell 80 at low cost.

[0097] Next, in the third manufacturing procedure, a 1 mm thick PC oil cell body 83 is bonded to 0.05 mm thick PC film (transmission window 85) cut to a 50 mm square size and placed on both side surfaces 83a, 83b using methylene dichloride, and then thoroughly dried to produce oil cell 80. The appearance of oil cell 80 obtained by this manufacturing procedure is similar to that of oil cell 80 obtained by the second manufacturing procedure described above.

[0098] In this manufacturing procedure, an organic solvent or the like is used to dissolve the surfaces of the PC oil cell body 83 and the PC transmission window 85. After the solvent evaporates, the melted portions are integrated and strongly bonded together, making this method suitable for use in environments requiring strong, airtight seals. While methylene dichloride is an example of a solvent, any solvent that dissolves resin surfaces may be used. This manufacturing procedure allows for the production of a simple oil cell 80 at low cost. Note that instead of a solvent, an adhesive may be used to bond the oil cell body 83 and the transmission window 85 together.

[0099] It should be noted that the present invention can be modified in various ways without departing from the spirit of the present invention, and it goes without saying that the present invention also covers such modifications. Furthermore, the above-described embodiments and modifications may be combined with each other.

[0100] Since the wave number and the wavelength are reciprocals of each other, they can be converted and interpreted accordingly. Furthermore, since transmittance and absorbance are correlated, the transmittance and absorbance in the above-described embodiments can be converted and interpreted accordingly.

[0101] It should be noted that the hydraulically driven working machine to which the present invention is applied is not limited to the construction machine described above, but may also be, for example, an automobile, a ship, an aircraft, a train, a wind power generator or a turbine, etc. The antioxidant replenishment system according to the present invention can also be applied to the automatic replenishment of automobile engine oil, etc. [Explanation of symbols]

[0102] 1: Hydraulic circuit 2: Oil tank 3: Hydraulic pump 4: Directional control valve 5: Actuator 6: Conduit 7: Dummy pipe 8: Pump 10, 50, 60, 70: Oil deterioration diagnostic device 20: Measuring part 21a~21c: Floodlights 22a~22c: Receiver 22d, 22e: Pyroelectric element 30: Diagnostic Department 31: Calculation section 32: Storage part 33: Judgment section 34:Notification Department 40: Replenishment Department 41: Refill tank 41a: Heater 42: Refill pump 43: Pump control unit 80: Oil cell 81a, 81b: Side 82: Observation window 83: Oil cell body 84: Oil storage section 85:Transparent window (resin film) 90: Holding case 91a, 91b: sensor holding surface 92: Gap

Claims

1. An oil deterioration diagnosis device for a work machine equipped with a hydraulic circuit, a measurement unit that irradiates oil in the hydraulic circuit with measurement light including at least first and second wave numbers different from each other, receives transmitted light that has passed through the oil, and outputs output values ​​that are current values ​​or voltage values ​​corresponding to the light intensities of the transmitted light at the first and second wave numbers; a calculation unit that calculates an output ratio that is a ratio of the output value at the first wave number to the output value at the second wave number; a storage unit in which a first threshold value of the output ratio in a used oil, which is oil that has been oxidized and consumed a predetermined amount of antioxidant, is stored in advance when the used oil is replenished with recovery oil containing the antioxidant; a determination unit that determines that it is time to replenish the used oil with the recovery oil when the output ratio for the used oil calculated by the calculation unit reaches the first threshold value; Equipped with the first wave number is a value within a measurement region that exhibits a characteristic infrared absorption in which the transmittance measured from the transmitted light that has passed through the oil decreases when the antioxidant contained in the used oil is consumed, an oil deterioration diagnosis device, characterized in that the second wave number is a value within a reference region that does not exhibit the characteristic infrared absorption even when the antioxidant contained in the used oil has been consumed.

2. An oil deterioration diagnosis device for a work machine equipped with a hydraulic circuit, a measurement unit that irradiates oil in the hydraulic circuit with measurement light including at least first and second wave numbers different from each other, receives transmitted light that has passed through the oil, and outputs output values ​​that are current values ​​or voltage values ​​corresponding to the light intensities of the transmitted light at the first and second wave numbers; a calculation unit that calculates an output ratio that is a ratio of the output value at the first wave number to the output value at the second wave number; a storage unit in which a second threshold value of the output ratio for used oil, which is oil containing a predetermined amount of oxides generated by oxidation, is stored in advance when the used oil is replaced with new oil, which is new oil; and a determination unit that determines that it is time to replace the used oil with the new oil when the output ratio for the used oil calculated by the calculation unit reaches the second threshold value; Equipped with the first wave number is a value within a measurement range that exhibits a characteristic infrared absorption in which the transmittance measured from the transmitted light that has passed through the oil decreases when the oxide is generated in the used oil, An oil deterioration diagnosis device characterized in that the second wave number is a value within a reference region that does not exhibit the characteristic infrared absorption even if the oxide is produced in the used oil.

3. 3. The oil deterioration diagnosis device according to claim 1, wherein the measurement unit measures the output values ​​at the first and second wave numbers of the oil flowing through the hydraulic circuit while the work machine is in operation.

4. 3. The oil deterioration diagnosis device according to claim 1, wherein the measurement unit measures the output values ​​at the first and second wave numbers of the oil flowing through a dummy pipe branched from the hydraulic circuit while the work machine is in operation.

5. 3. The oil deterioration diagnosis device according to claim 1, wherein the measurement unit measures the output values ​​of the oil extracted from the hydraulic circuit at the first and second wave numbers.

6. an oil cell comprising: an oil cell main body; an oil storage section that opens on both side surfaces of the oil cell and is capable of storing the oil extracted from the main body hydraulic circuit; and a pair of transmission windows that close the openings on both side surfaces of the oil cell so as to sandwich the oil storage section; a light projector that projects the measurement light toward the transmission window, and a light receiver that receives the transmitted light that has passed through the transmission window and the oil contained in the oil container; and a holding case that can accommodate the oil cell; 6. The oil deterioration diagnosis device according to claim 5, further comprising:

7. The oil cell body is formed by resin injection molding, 7. The oil deterioration diagnostic device according to claim 6, wherein the transmission window is a resin film.

8. 8. The oil deterioration diagnostic device according to claim 7, wherein the resin film is insert-molded when the oil cell body is resin-injected.

9. 8. The oil deterioration diagnostic device according to claim 7, wherein the resin film is bonded to both side surfaces of the oil cell body by electrostatic force.

10. 8. The oil deterioration diagnostic device according to claim 7, wherein the resin film is bonded to both side surfaces of the oil cell body via a solvent.

11. 8. The oil deterioration diagnostic device according to claim 7, wherein the resin film is bonded to both side surfaces of the oil cell body via an adhesive.

Images