Oil change notification device and work machine

Abstract

To provide an oil change determination and notification device capable of appropriately determining a change timing of oil, and capable of notifying that it is time to change oil.SOLUTION: An oil change determination and notification device for determining and notifying an operator of a change timing of oil for operating a hydraulic drive device includes an acquisition section for acquiring density and temperature of oil, an arithmetic section for calculating the density acquired by the acquisition section for density at a prescribed oil temperature, a determining section for determining a timing at which the oil should be changed on the basis of the density calculated by the arithmetic section, and a notifying device for notifying that it is time to change the oil when the determining section determines that it is time to change the oil.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an oil change notification device and a work machine. [Background technology]

[0002] BACKGROUND ART A work machine disclosed in Patent Document 1 is known as a work machine capable of estimating the oil change timing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7009408 Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art, there was room for consideration in determining the appropriate timing for oil change. An object of the present invention is to provide an oil change determination / notification device and a work machine that can appropriately determine when it is time to change oil and notify the user that it is time to change the oil. [Means for solving the problem]

[0005] An oil change determination and notification device according to one aspect of the present invention is an oil change determination and notification device that determines and notifies the time to change oil that operates a hydraulic drive system, and includes: an acquisition unit that acquires the density and oil temperature of the oil; a calculation unit that calculates the density acquired by the acquisition unit to a density at a predetermined oil temperature; and a determination unit that determines the time to change the oil based on the density calculated by the calculation unit. a variance calculation unit that calculates the variance of the density calculated by the calculation unit; and a notification device that notifies the user that it is time to change the oil when the determination unit determines that it is time to change the oil. When the density variance calculated by the variance calculation unit exceeds a predetermined upper threshold, the judgment unit determines that there is a deterioration in antifoaming performance or an increase in contamination, and that it is time to change the oil.

[0006] The determination unit may determine that air bubbles have been mixed into the oil when the density calculated by the calculation unit falls below a predetermined lower threshold, and the alarm device may be configured to notify the fact that air bubbles have been mixed into the oil and to suggest maintenance of the machine when the determination unit determines that air bubbles have been mixed into the oil. The determination unit may determine when the oil should be changed and the reason for changing the oil by quantitatively evaluating the density of the oil based on the density calculated by the calculation unit.

[0007] When the density calculated by the calculation unit exceeds a predetermined upper threshold, the determination unit determines that the oil has oxidized and / or the amount of contaminants mixed in the oil has increased, and determines that it is time to change the oil, and the alarm device may be configured to notify that the reason for changing the oil is that the oil has oxidized and / or the amount of contaminants mixed in the oil has increased, and that it is time to change the oil.

[0008] The oil change determination notification device may include a variance calculation unit that calculates the variance of the density calculated by the calculation unit, and when the variance of the density calculated by the variance calculation unit exceeds a predetermined upper threshold, the determination unit determines that there has been a deterioration in anti-foaming performance or an increase in contamination, and determines that it is time to change the oil, and the notification device may notify that the reason for changing the oil is the deterioration in anti-foaming performance or the increase in contamination, and that it is time to change the oil.

[0009] An oil change determination and notification device according to another aspect of the present invention is an oil change determination and notification device that determines and notifies the time to change oil that operates a hydraulic drive unit, and includes: an acquisition unit that acquires the density and oil temperature of the oil; a calculation unit that calculates the density acquired by the acquisition unit to a density at a predetermined oil temperature; a determination unit that determines when the oil should be changed based on the density calculated by the calculation unit; and a notification device that notifies the time to change the oil when the determination unit determines that it is time to change the oil. The oil temperature sensor includes a recording unit that records data on the relationship between oil temperature and density when the oil temperature of the oil drops within a predetermined temperature range, and a coefficient calculation unit that calculates a temperature dependency coefficient by performing linear regression on the data on the relationship between oil temperature and density recorded in the recording unit, and the calculation unit calculates the density acquired by the acquisition unit into a density at the predetermined temperature using the temperature dependency coefficient. do.

[0010] The oil change determination notification device may include a measurement sensor that measures the density and oil temperature of the oil, the acquisition unit acquires the density and oil temperature from the measurement sensor, and the calculation unit calculates the density at the oil temperature obtained from the measurement sensor to the density at the specified temperature. A working machine according to one aspect of the present invention is provided with the oil change determination notification device and a gear-type transmission. In the working machine equipped with the gear-type transmission, the oil also serves as lubricating oil for the gear-type transmission.

[0011] The work machine may include a hydrostatic continuously variable transmission, a supply line that supplies the oil to a charge circuit of the hydrostatic continuously variable transmission, an oil filter provided in the supply line, and a measurement sensor that measures at least one of the oil density and oil temperature acquired by the acquisition unit, and the measurement sensor may be configured to measure the oil flowing upstream or downstream of the oil filter in the supply line.

[0012] The work machine may include a hydrostatic continuously variable transmission, a supply line that supplies the oil to a charge circuit of the hydrostatic continuously variable transmission, a return line through which the oil returning from the supply line flows, an oil cooler provided in the return line, and a measurement sensor that measures at least one of the oil density and oil temperature acquired by the acquisition unit, and the measurement sensor may be configured to perform the measurement of the oil flowing upstream or downstream of the oil cooler in the return line.

[0013] The work machine may include steering wheels, a steering cylinder that steers the steering wheels, a hydraulic controller that receives the oil and operates the steering cylinder, and a measurement sensor that measures at least the density or oil temperature of the oil acquired by the acquisition unit, and the measurement sensor may be configured to measure the oil supplied to the hydraulic controller or the oil returning from the hydraulic controller.

[0014] The work machine includes a vehicle body, a lifting cylinder that lifts and lowers an implement attached to the vehicle body, and a lifting control valve that is supplied with the oil and controls the lifting cylinder. The oil supply system may further include a measurement sensor that measures at least one of the oil density and oil temperature acquired by the acquisition unit, and the measurement sensor may be configured to measure the oil discharged from the lift control valve, the oil supplied to the lift control valve, or the oil returning from the lift cylinder. [Effects of the Invention]

[0015] According to the above configuration, the density of the oil is calculated to the density at a predetermined oil temperature, and the time to change the oil is determined based on this calculated density, so that the time to change the oil can be appropriately determined and an alert can be given that it is time to change the oil. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a side view of a tractor as a work machine. [Figure 2] FIG. 2 is a circuit diagram showing a hydraulic system. [Figure 3] FIG. 2 is a diagram illustrating the configuration of an oil change determination notification device. [Figure 4] 4 is a flowchart showing the processing operation of the oil change determination notification device. [Figure 5] 1 is a graph showing the relationship between density and time. [Figure 6] 1 is a graph showing the relationship between density and time. [Figure 7] 1 is a graph showing the relationship between density and time. [Figure 8] 1 is a graph showing the relationship between density variance and time. [Figure 9] FIG. 2 is a circuit diagram showing the installation locations of measurement sensors. [Figure 10] FIG. 2 is a circuit diagram showing the installation locations of measurement sensors. [Figure 11] FIG. 2 is a circuit diagram showing the installation locations of measurement sensors. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. 1 is a schematic side view showing the overall configuration of a work machine 1 according to this embodiment. In this embodiment, a tractor is shown as an example of the work machine 1. As shown in Figure 1, the tractor 1 has a body 2, front wheels 4 arranged on the left and right of a front frame 3 that supports the front of the body 2, rear wheels 5 arranged on the left and right of the rear of the body 2, and a driver's section 8 arranged above the body 2 and equipped with a steering wheel 6, a driver's seat 7 in which an operator sits, etc.

[0018] A hydraulic device 9 for lifting and lowering a work implement and a power take-off shaft (referred to as a PTO shaft) 10 are provided at the rear of the vehicle body 2. The hydraulic device 9 for lifting and lowering a work implement is connected to a connecting device such as a three-point linkage at the rear of the vehicle body 2. The PTO shaft 10 is a shaft for extracting power from the tractor 1 in order to transmit power from the tractor 1 to the implement.

[0019] The vehicle body 2 has an engine (prime mover) 11 supported by the front frame 3, a housing case 12 connected to the rear of the engine 11, and a transmission case 13 connected to the rear of the housing case 12. The housing case 12 accommodates a flywheel 14 that stabilizes the rotation of the crankshaft of the engine 11, a main clutch 15 that transmits power from the flywheel 14 intermittently, and the like.

[0020] The transmission case 13 is configured by connecting a first case 17 that houses a hydrostatic continuously variable transmission (HST) 16 and a second case 19 that houses a gear-type transmission 18. The HST 16 transmits power from the main clutch 15 to the gear-type transmission 18. The gear-type transmission 18 has a traveling system transmission and a PTO system transmission. The traveling system transmission transmits the power output from the HST 16 to a rear wheel differential and also to the rear wheels 5 (drive wheels) via the rear wheel differential. The PTO system transmission transmits the power from the main clutch 15 to the PTO shaft 10 before it is shifted by the HST 16. In other words, the HST 16 transmits power to the traveling system transmission in the gear-type transmission 18, but does not transmit power to the PTO system transmission.

[0021] The second case 19 stores transmission oil (oil), which is a lubricating oil that lubricates the gear transmission 18, the rear wheel differential, etc. In the tractor 1, this oil also serves as hydraulic oil to operate the hydraulic drive system equipped in the tractor 1. In other words, the tractor 1 is equipped with a hydraulic drive system that is driven by hydraulic pressure, and the transmission oil is used as the hydraulic oil to operate this hydraulic drive system. The second case 19 is an oil tank (oil storage section) in which oil is stored.

[0022] FIG. 2 shows the hydraulic system (hydraulic circuit) of the tractor 1. The hydraulic system includes hydraulic drive devices such as a power steering device 21, HST 16, a hydraulic device 9 for lifting and lowering a work implement, and a clutch actuation device 22, which are driven by oil (hydraulic pressure) that also serves as transmission oil. The hydraulic system also includes a plurality of hydraulic pumps 23 that suck in and discharge oil stored in a second case 19. The plurality of hydraulic pumps 23 include a first pump 23A, a second pump 23B, and a third pump 23C. The first pump 23A, the second pump 23B, and the third pump 23C are configured as fixed displacement hydraulic pumps driven by the engine 11. It should be noted that at least one hydraulic pump is sufficient.

[0023] The power steering device 21 has a steering cylinder 24 that steers the left and right front wheels 4 (steered wheels), and a hydraulic controller 25 that operates the steering cylinder 24. The hydraulic controller 25 has a steering valve 26 that is operated by the steering wheel 6 to switch the direction of oil, a metering pump 27 that measures and supplies an amount of oil according to the degree of rotation of the steering wheel 6 to the steering cylinder 24, a relief valve 28, and a check valve 29. The hydraulic controller 25 (steering valve 26) is supplied with oil discharged from the second pump 23B.

[0024] The HST 16 includes a swash plate-type variable displacement pump (referred to as an HST pump) 31 and an HST motor 33 that is connected to the HST pump 31 via a pair of speed-change oil passages 32a and 32b in a closed circuit and is driven by oil discharged from the HST pump 31 to output power. The HST 16 also includes a servo cylinder 34 that controls the swash plate of the HST pump 31, a swash plate control valve 35 that controls the servo cylinder 34, and a charge circuit 36 ​​that replenishes oil to the pair of speed-change oil passages 32a and 32b. Oil discharged from the third pump 23C is supplied to the charge circuit 36 ​​via a supply line 37. An oil filter (HST filter) 38 is provided in the supply line 37. A return line 39 is connected to the supply line 37, through which oil returns from the supply line 37 to the second case 19. The return line 39 is provided with a relief valve 40 and an oil cooler 41 located downstream of the relief valve 40.

[0025] On the other hand, the oil flowing through the supply pipe 37 after passing through the oil filter 38 is branched and supplied to the swash plate control valve 35 and the clutch actuator 22 via a pressure compensation valve 42 . The work implement lifting hydraulic system 9 has a hydraulic case 43, lifting cylinders 44 that raise and lower lift arms disposed on the left and right of the hydraulic case 43, a lifting control valve 45 that controls the lifting cylinders 44, a lowering speed adjustment valve 68 that controls the lowering speed of the implement connected to the connecting mechanism, and a safety valve 46 for the lifting cylinders 44. The work implement lifting hydraulic system 9 (lifting control valve 45) is supplied with oil discharged from the first pump 23A.

[0026] The lift arm is connected to a connecting mechanism (three-point linkage) via a lift rod. The lift cylinder 44 is composed of a single-acting hydraulic cylinder that swings the lift arm upward when oil is supplied to it and swings the lift arm downward when oil is discharged. The lift arm moves up and down, thereby raising and lowering the connecting mechanism and the implement. In other words, the lift cylinder 44 is a hydraulic cylinder that raises and lowers the implement attached to the vehicle body 2. The lift control valve 45 includes a main spool valve 69. The main spool valve 69 is switchable among a position where oil supplied from the first pump 23A is supplied to the lift cylinder 44, a position where oil discharged from the lift cylinder 44 is returned to the second case 19 via the descent speed adjustment valve 68 and the shutoff valve 70, and a position where oil supplied from the first pump 23A is returned to the second case 19 but oil is not discharged from the lift cylinder 44.

[0027] The clutch operating device 22 is a device that operates a clutch that interrupts the power transmission of the PTO system transmission mechanism, and has a clutch operating cylinder 20 that operates the clutch, and a clutch operating valve 30 that operates the clutch operating cylinder 20. However, there are concerns that oil degradation due to air bubbles, oxidation, and / or an increase in contaminants (wear particles, moisture) mixed into the oil can cause problems for machinery. There is also concern that oil degradation can lead to a decline in anti-foaming performance, which can cause problems for machinery. To prevent machine breakdowns and other issues caused by oil degradation, recommended oil change intervals are established through market surveys, bench tests, vehicle tests, and other reproduction tests. However, because the degree of oil degradation varies depending on individual machine characteristics, the user's usage conditions, and the usage environment, it is difficult to determine the appropriate oil change interval based on the length of time the oil has been used.

[0028] Therefore, the tractor 1 of this embodiment is provided with an oil change determination / notification device 47 (see FIG. 3) that can determine the appropriate time to change the oil and notify the operator that it is time to change the oil. As shown in FIG. 3, the oil change determination / notification device 47 includes a measurement sensor 48, a determination device 49, and a notification device 50. The measurement sensor 48 measures the density and temperature of the oil. Specifically, the measurement sensor 48 is made up of a plurality of sensors, including a density sensor 48A that measures the density of the oil and a temperature sensor 48B that measures the temperature of the oil.

[0029] The measurement sensor 48 may be a single sensor that measures the density and oil temperature (a single sensor body having the function of measuring the density and oil temperature). In order to ensure stable measurements and to constantly monitor the oil, it is desirable to install the measurement sensor 48 in a location where there is a flow of oil circulating through the hydraulic system and where the oil pressure (oil pressure) is maintained within a range that does not cause problems for the sensor's operation. Also, it can be said that a suitable location for installing the measurement sensor 48 is somewhere in the pipeline connecting the hydraulic components.

[0030] FIG. 2 shows an example of the location of the measurement sensor 48, indicated by the symbol A1. As shown in FIG. 2, in this embodiment, the measurement sensor 48 (density sensor 48A, temperature sensor 48B) is provided in the supply line 37, in the line 37a between the third pump 23C and the oil filter 38. Specifically, the measurement sensor 48 is provided upstream of and in the vicinity of the oil filter 38, and measures the density and oil temperature of the oil flowing upstream of the oil filter 38. A relief valve 40 is often provided near the oil filter 38, making this a suitable location for providing the measurement sensor 48. Providing the measurement sensor 48 upstream of the oil filter 38 also has the advantage that, if the measurement sensor 48 is damaged, debris will not flow through the hydraulic circuit and reach and damage hydraulic equipment. Another advantage is that the measurement sensor 48 can be easily installed near the oil filter 38.

[0031] The determination device 49 is configured using, for example, a microcomputer equipped with a CPU, an EEPROM, etc. A density sensor 48A and a temperature sensor 48B are connected to the determination device 49, and the density measured by the density sensor 48A and the oil temperature measured by the temperature sensor 48B are input to the determination device 49. The determination device 49 includes an acquisition unit 51 , a calculation unit 52 , a storage unit 53 , a determination unit 54 , an output unit 55 , a variance calculation unit 76 , a recording unit 56 , and a coefficient calculation unit 57 .

[0032] The acquisition unit 51 acquires the density and oil temperature of the oil. Specifically, the acquisition unit 51 acquires the density and oil temperature obtained from the measurement sensors 48 (density sensor 48A, temperature sensor 48B). The density and oil temperature obtained from the measurement sensor 48 may be the measured values ​​themselves, or may be values ​​(approximate values) obtained by rounding the measured values ​​after performing fractional rounding. The calculation unit 52 converts the density acquired by the acquisition unit 51 into a density at a predetermined oil temperature. In other words, the calculation unit 52 converts the density obtained from the density sensor 48A at the oil temperature obtained from the temperature sensor 48B into a density at a predetermined oil temperature (for example, 100°C). Note that the predetermined temperature is not limited to 100°C.

[0033] While physical properties such as oil density are linearly dependent (proportional) to temperature, the coefficients can vary depending on factors such as the oil lot, making it desirable to calculate them as needed. While oil contamination (foreign matter) and differences in equipment operating conditions can contribute to noise, this can be eliminated by using data from large temperature changes that occur over a short period of time. To accurately estimate the oil's physical properties, the calculation unit 52 converts the density obtained from the density sensor 48A into the density at a given temperature using a temperature-dependent coefficient determined from the oil temperature-density relationship data when the oil temperature falls within a predetermined temperature range.

[0034] For example, when the oil temperature drops suddenly (temperature changes), such as immediately after the engine 11 is stopped, the oil temperature-density relationship data is recorded, a linear regression is performed on this relationship data to calculate a temperature dependency coefficient, and the density obtained from the density sensor 48A is converted to the density at a specified temperature using this temperature dependency coefficient. Furthermore, the oil temperature during operation varies within a temperature range of, for example, approximately 50° C. to approximately 80° C. Furthermore, since the density of oil varies depending on the temperature, in order to use the density at the same temperature to determine the timing and reason for changing the oil, the calculation unit 52 converts the density at the oil temperature obtained from the measurement sensor 48 into, for example, the density when the oil temperature is 100° C. (density at 100° C.).

[0035] The memory unit 53 stores in advance a lower density threshold value, which is a criterion for determining whether air bubbles have been mixed into the oil; an upper density threshold value, which is a criterion for determining whether the oil has oxidized and / or whether there has been an increase in contaminants mixed into the oil; and an upper density variance threshold value, which is a criterion for determining whether the oil's defoaming performance has deteriorated or whether there has been an increase in contaminants. The density thresholds (lower limit threshold, upper limit threshold) and density variance thresholds (upper limit threshold) are determined as physical quantities, for example, from the results of bench tests prepared in advance. In other words, the density thresholds and density variance thresholds are determined based on the 100°C density data from bench tests. The density thresholds (lower limit threshold, upper limit threshold) and density variance thresholds may also be determined as the relative amount of change from when the oil was new.

[0036] Oxidation is a change that occurs when oil reacts with oxygen in the air, and contamination refers to foreign matter such as wear particles (metal wear particles) and moisture that get mixed into the oil. The determination unit 54 determines when the oil should be changed based on the density (density at 100°C) calculated by the calculation unit 52. Specifically, it determines that it is time to change the oil when the density at 100°C exceeds an upper threshold value or when the variance of the density at 100°C exceeds an upper threshold value.

[0037] Furthermore, the determining unit 54 determines the reason for the oil change based on the density (density at 100°C) calculated by the calculating unit 52. In detail, when the density at 100°C exceeds the upper threshold, the determining unit 54 determines that the reason for the determination of the time to change the oil is oil oxidation and / or oil stagnation. If the variance in density at 100°C exceeds the upper threshold, it is determined that the reason for determining when to change the oil is a deterioration in antifoaming performance or an increase in contamination.

[0038] That is, the determining unit 54 quantitatively evaluates the deterioration of the oil based on the density calculated by the calculating unit 52, thereby determining when the oil should be changed and the reason why the oil should be changed. Furthermore, the determination unit 54 determines that maintenance is required for the machine (oil) equipped with the oil change determination notification device 47 based on the density (100°C density) calculated by the calculation unit 52. More specifically, when the 100°C density falls below the lower limit threshold, the determination unit 54 determines that air bubbles have been mixed into the oil and that maintenance of the machine is required.

[0039] When the determination unit 54 determines that it is time to change the oil, the output unit 55 outputs a signal (alert signal) indicating that it is time to change the oil to the alarm device 50. The output unit 55 also outputs the reason for changing the oil, determined by the determination unit 54, to the alarm device 50. More specifically, when the reason for determining that it is time to change the oil is oil oxidation and / or an increase in contaminants mixed in the oil, the output unit 55 outputs a signal indicating that the reason for changing the oil is oil oxidation / contamination to the alarm device 50. When the reason for changing the oil is deterioration of anti-foaming performance or an increase in contaminants, the output unit 55 outputs a signal indicating that the reason for changing the oil is deterioration of anti-foaming performance or an increase in contaminants to the alarm device 50. When the output unit 55 determines that air bubbles have mixed in the oil and that machine maintenance is required, the output unit 55 outputs a signal indicating that air bubbles have mixed in the oil and urging the user to perform machine maintenance to the alarm device 50.

[0040] The variance calculation unit 76 calculates the variance of the density (density at 100° C.) calculated by the calculation unit 52 using a calculation formula stored in the oil change determination notification device 47. The recording unit 56 records the data on the relationship between oil temperature and density when the oil temperature drops within a predetermined temperature range (when the oil temperature drops suddenly). The coefficient calculation unit 57 performs linear regression on the oil temperature-density relationship data recorded in the recording unit 56 to calculate a temperature-dependent coefficient.

[0041] The notification device 50 is a device that can notify an operator that it is time to change the oil, the reason for the oil change, and that the machine should be maintained, and is configured, for example, as a display device having a display unit that can display text that it is time to change the oil, the reason for the oil change, and that the machine should be maintained. The notification device 50 may also be a voice generating device that can notify the operator that it is time to change the oil, etc., by voice. The display device may also be equipped with a voice generating device in addition to a display unit that can display text. The display device may also be equipped with an alarm sound generating device that can notify the operator that it is time to change the oil by sound, such as a buzzer.

[0042] The notification device 50 is connected to the determination device 49 and receives a signal output from the output unit 55 (determination device 49). Upon receiving the signal output from the output unit 55, the notification device 50 notifies the driver that it is time to change the oil and the reason why the oil should be changed. The notification device 50 is provided, for example, in the driver's section 8, and preferably in the vicinity of the driver's seat 7. In addition, when the notification device 50 is configured as a display device, it is preferable that it is provided in a position that is easily visible to the operator seated in the driver's seat 7. 4 is a flowchart showing the processing operation of the oil change determination notification device 47. The processing operation of the oil change determination notification device 47 will be described using this flowchart.

[0043] The processing operation begins after the engine 11 is started, and is performed in real time or at predetermined timing while the engine 11 is running. After starting the processing operation, the oil change determination notification device 47 first measures the density and oil temperature using the density sensor 48A and the temperature sensor 48B (step S1). In practice, the acquisition unit 51 acquires the density and oil temperature obtained from the density sensor 48A and the temperature sensor 48B. Once the density and oil temperature are measured, the process proceeds to step S2, where temperature correction of the density is performed by the calculation unit 52. Specifically, the calculation unit 52 calculates the density acquired by the acquisition unit 51 (density at the oil temperature at the time of measurement) into density at a predetermined temperature (density at 100°C).

[0044] Next, the determining unit 54 determines whether the density at 100° C. is below the lower limit threshold (lower limit threshold for density) (step S3). If the 100°C density falls below the lower threshold (step S3: YES), the judgment unit 54 determines that air bubbles have been mixed into the oil (step S4), the output unit 55 outputs a message to the alarm device 50 indicating that air bubbles have been mixed into the oil and that machine maintenance is required, and the alarm device 50 then issues a message indicating that air bubbles have been mixed into the oil and that machine maintenance is required (step S5). Here, FIG. 5 is a graph showing the relationship between density and time, with the horizontal axis representing time and the vertical axis representing density, and shows how the density changes when the density falls below the lower threshold.

[0045] In FIG. 5, reference numeral 58 denotes a lower limit threshold of density, for example, 0.76 gcc. Normally, the density value increases as the oil is used over time, but if the density value decreases, it is possible to suspect that air bubbles have been mixed into the oil. As shown in Figure 5, if the density falls below the lower threshold (see reference numeral 60), it can be determined that a predetermined amount or more of air bubbles have been mixed into the oil.

[0046] When making this determination, if the density suddenly drops below the lower threshold and then immediately (in a short time) rises above the lower threshold, the determination unit 54 will not determine that the density has fallen below the lower threshold. In other words, in Figure 5, the graph (density value) may drop in a spike-like manner as indicated by reference numeral 59, but in such a case, it will not be determined that it is time to change the oil. As shown by the symbol 60 in Figure 5, if the density is below the lower threshold and remains below the lower threshold for a predetermined time, the judgment unit 54 determines that the density is below the lower threshold and that a predetermined amount or more of air bubbles have become mixed into the oil.

[0047] Furthermore, if the 100°C density is not below the lower threshold (step S3: NO), the determining unit 54 determines whether the 100°C density exceeds the upper threshold (upper density threshold) (step S6). If the 100°C density exceeds the upper threshold (step S6: YES), the judgment unit 54 determines that the oil has oxidized and / or that there is an increase in contaminants mixed in the oil (step S7), and the output unit 55 outputs to the alarm device 50 a message indicating that there is an increase in oil oxidation and / or contaminants mixed in the oil and that it is time to change the oil, and the alarm device 50 reports that there is an increase in oil oxidation and / or contaminants mixed in the oil and that it is time to change the oil (step S8).

[0048] Here, FIG. 6 is a graph showing the relationship between density and time, with the horizontal axis representing time and the vertical axis representing density, and shows how the density changes when it exceeds the upper threshold value. In FIG. 6, reference numeral 61 denotes the upper threshold of density, which is, for example, 0.845 gcc. Typically, the density value increases as the oil ages. This is thought to represent changes in the oil due to increased oil oxidation and / or increased contaminants mixed in the oil. As shown in FIG. 6, when the density exceeds the upper threshold (see reference numeral 63), it is determined that it is time to change the oil, and the reason for the oil change is determined to be increased oil oxidation and / or increased contaminants mixed in the oil.

[0049] When making this determination, if the density rises sharply, exceeds the upper threshold, and then immediately (in a short time) falls below the upper threshold, the determination unit 54 will not determine that the density has exceeded the upper threshold. In other words, in Figure 6, the graph (density value) may rise in a spike-like manner as indicated by the reference numeral 62, but in such a case, it will not be determined that it is time to change the oil. As shown by the symbol 63 in Figure 6, if the density exceeds the upper threshold and continues to exceed the upper threshold for a predetermined period of time, the judgment unit 54 determines that the density has exceeded the upper threshold, and determines that it is time to change the oil, and that the reason for the oil change is oil oxidation or an increase in contaminants mixed in the oil.

[0050] On the other hand, in step S6, if the 100°C density does not exceed the upper limit threshold (step S6: NO), the process proceeds to step S9, where the variance calculation unit 76 calculates the variance of the 100°C density. Next, the determining unit 54 determines whether or not the 100° C. density variance exceeds the upper threshold (upper threshold of density variance) (step S10).

[0051] If the variance of the 100°C density exceeds the upper threshold (step S10: YES), the judgment unit 54 judges that the reason for the oil change is a deterioration in the anti-foaming performance or an increase in contamination (step S11), and the output unit 55 outputs to the alarm device 50 a message that the reason for the oil change is a deterioration in the anti-foaming performance or an increase in contamination, and that it is time to change the oil, and the alarm device 50 reports that the reason for the oil change is a deterioration in the anti-foaming performance or an increase in contamination, and that it is time to change the oil (step S12).

[0052] In step S10, if the variance of the 100°C density does not exceed the upper limit threshold (step S10: NO), the process returns to step S1, and the processing operations from step S1 onwards are executed. Here, FIG. 7 is a graph showing the relationship between density and time, with time on the horizontal axis and density on the vertical axis, and shows how the density variance increases with the passage of time of use.

[0053] The density variance is the width in the vertical direction of the graph (the distance between the maximum and minimum density values ​​over a short period of time) indicated by reference numeral 77 in Figure 7. If the density variance increases, it can be suspected that air bubbles have been mixed in due to a deterioration in defoaming performance, or that there is an increase in contamination. Figure 8 is a graph showing the relationship between density variance and time, with time on the horizontal axis and density variance on the vertical axis, and shows how the density variance changes when it exceeds the upper threshold.

[0054] In Fig. 8, reference numeral 78 denotes an upper threshold value of the density variance. As shown in Fig. 8, the value of the density variance increases with the deterioration of the defoaming performance or the increase of contamination, and when the density variance exceeds the upper threshold value (see reference numeral 80), it is determined that it is time to change the oil, and that the reason for changing the oil is the deterioration of the oil's defoaming performance or the increase of contamination.

[0055] When making this determination, if the density variance suddenly rises and exceeds the upper threshold, and then immediately (in a short time) falls below the upper threshold, the determination unit 54 will not determine that the density variance has exceeded the upper threshold. In other words, in Figure 8, the graph (density variance value) may rise in a spike-like manner as indicated by reference numeral 79, but in such a case, it will not be determined that it is time to change the oil. As shown by the reference symbol 80 in FIG. 8 , when the density variance exceeds the upper limit threshold and continues to exceed the upper limit threshold for a predetermined time, the judgment unit 54 judges that the density variance has exceeded the upper limit threshold, and determines that it is time to change the oil, and that the reason for changing the oil is deterioration of the defoaming performance or an increase in contamination.

[0056] The notification by the notification device 50 that it is time to change the oil, that the reason for changing the oil is oxidation of the oil, an increase in contaminants mixed in the oil, or a deterioration in the defoaming performance or an increase in contaminants, that machine maintenance is required, and that machine maintenance is required because air bubbles have mixed in the oil are made, for example, while the engine 11 is running. The notification may also be made when the engine 11 is started or when the engine 11 is turned off.

[0057] As described above, in this embodiment, it is possible to appropriately determine the oil change timing, which varies depending on individual differences between machines and the user's operating conditions and environment, and to notify the user (operator) of the oil change timing. The present invention is not limited to the above-described embodiments. For example, the acquisition unit 51 may acquire the oil density and oil temperature from a source other than the measurement sensor 48. In other words, the measurement sensor 48 may be a sensor that measures at least one of the oil density and oil temperature for which the acquisition unit 51 acquires the oil density and oil temperature.

[0058] In addition, the oil change determination notification device 47 may be configured to retain the reason for changing the oil as data rather than outputting the reason for changing the oil immediately after determining that the oil should be changed, and to output the reason for changing the oil to the notification device 50 when some operation is performed. Furthermore, the installation location of the measurement sensor 48 is not limited to the above-mentioned installation location A1. Other examples of installation locations of the measurement sensor 48 are shown in Figs.

[0059] The measurement sensor 48 may be installed in the supply pipe 37, in the pipe 37b downstream of the oil filter 38, as shown by reference symbol A2 in FIG. 9. That is, the measurement sensor 48 may be installed in the supply pipe 37 downstream of and near the oil filter 38, and measure the density and oil temperature of the oil flowing downstream of the oil filter 38. The measurement sensor 48 may also be installed in the return pipe 39, through which oil flows from the supply pipe 37 to the second case 19, in the pipe 39a downstream of the oil cooler 41, as shown by reference symbol A3 in FIG. 9, or in the pipe 39b upstream of the oil cooler 41, as shown by reference symbol A4 in FIG. 9. That is, the measurement sensor 48 may be installed in the return pipe 39, upstream or downstream of the oil cooler 41, and measure the density and oil temperature of the oil flowing upstream or downstream of the oil cooler 41. 9, the installation location may be set in the pipeline 65 downstream of the suction filter (oil filter) 64. In other words, the measurement sensor 48 may be installed downstream of the suction filter 64 to measure the density and oil temperature of the oil flowing downstream of the suction filter 64.

[0060] 10, the measurement sensor 48 may be set in a pipe (oil supply path) 66 that supplies oil to the hydraulic controller 25, as shown by reference symbol A6, or in a pipe (oil return path) 67 that returns oil from the hydraulic controller 25 to the second case 19, as shown by reference symbol A7 in Fig. 10. In other words, the measurement sensor 48 may be installed in the oil supply path 66 or the oil return path 67 to measure the density and oil temperature of the oil supplied to the hydraulic controller 25 or the oil returned from the hydraulic controller 25.

[0061] When the steering wheel 6 is not operated, the steering inflow pressure in the oil return line 67 is, for example, about 2.5 to 3 MPa, and when the steering wheel 6 is operated, the pressure becomes negative. This is a pressure suitable for installing a sensor. Although not limited to this, in a tractor 1 that is not equipped with an HST 16, the measurement sensor 48 can be installed in the return pipe (oil return line 67) from this hydraulic controller 25.

[0062] In addition, the installation location of the measurement sensor 48 may be set in a pipeline 71 (first oil drain pipeline 71A, second oil drain pipeline 71B, third oil drain pipeline 71C) that discharges oil from the lift control valve 45, as shown by symbols A8 to A10 in Figure 11, or in a pipeline (oil supply path) 72 that supplies oil to the lift control valve 45, as shown by symbol A11 in Figure 11, or in a pipeline (oil return path) 73 that returns oil from the lift cylinder 44 to the second case 19 via the safety valve 46 for the lift cylinder 44, as shown by symbol A12 in Figure 11. In other words, the measurement sensor 48 may be installed in the first oil drain line 71A, the second oil drain line 71B, the third oil drain line 71C, the oil supply line 72 or the oil return line 73, and may be configured to measure the density and oil temperature of the oil discharged from the lift control valve 45, the oil supplied to the lift control valve 45, or the oil returning from the lift cylinder 44.

[0063] The measurement sensor 48 installed in the oil supply passage 72 is located between the first pump 23A and a connection 75a of a relief circuit 75 having a relief valve 74 that sets the discharge pressure of the first pump 23A. The measurement sensor 48 installed in the oil return path 73 is set downstream of the safety valve 46 for the lift cylinder 44 . The installation location of the measurement sensor 48 is not limited to the locations shown in Figures 9 to 11. Furthermore, at the installation location, the measurement sensor 48 that measures at least one of the oil density and oil temperature acquired by the acquisition unit 51 is installed.

[0064] The oil change determination notification device 47 of this embodiment is an oil change determination notification device 47 that determines and notifies when it is time to change the oil that operates the hydraulic drive device, and is equipped with an acquisition unit 51 that acquires the oil density and oil temperature, a calculation unit 52 that calculates the density acquired by the acquisition unit 51 to the density at a predetermined oil temperature, a determination unit 54 that determines when the oil should be changed based on the density calculated by the calculation unit 52, and a notification device 50 that notifies that it is time to change the oil when the determination unit 54 determines that it is time to change the oil.

[0065] According to this configuration, the density of the oil is calculated to the density at a predetermined oil temperature, and the timing for changing the oil is determined based on this calculated density, so that the timing for changing the oil can be determined appropriately. and can notify the user that it is time to change the oil. If the density calculated by the calculation unit 52 falls below a preset lower threshold 58, the determination unit 54 determines that air bubbles have been mixed into the oil, and if the determination unit 54 determines that air bubbles have been mixed into the oil, the notification device 50 notifies the user that air bubbles have been mixed into the oil and suggests maintenance of the machine. According to this configuration, if air bubbles are mixed into the oil, a suggestion for machine maintenance can be notified.

[0066] The determining unit 54 quantitatively evaluates the oil density based on the density calculated by the calculating unit 52, and determines when the oil should be changed and the reason for changing the oil. This configuration not only notifies the driver when it is time to change the oil, but also the reason why the oil should be changed. When the density calculated by the calculation unit 52 exceeds a preset upper threshold 61, the judgment unit 54 determines that the oil has oxidized and / or the amount of contaminants mixed in the oil has increased, and determines that it is time to change the oil.The alarm device 50 then notifies the user that the reason for changing the oil is that the oil has oxidized and / or the amount of contaminants mixed in the oil has increased, and that it is time to change the oil.

[0067] According to this configuration, when the oxidation of the oil and / or the amount of contaminants mixed in the oil increases, it is possible to notify the reason why the oil should be changed and that it is time to change the oil. The oil change determination notification device 47 also includes a variance calculation unit 76 that calculates the variance of the density calculated by the calculation unit 52. When the variance of the density calculated by the variance calculation unit 76 exceeds a preset upper threshold 78, the determination unit 54 determines that there has been a deterioration in anti-foaming performance or an increase in contamination, and determines that it is time to change the oil. The notification device 50 then notifies the user that the reason for the oil change is the deterioration in anti-foaming performance or the increase in contamination, and that it is time to change the oil.

[0068] According to this configuration, when the antifoaming performance of the oil deteriorates, it is possible to notify the reason why the oil should be changed and to inform the driver that it is time to change the oil. The oil change determination notification device 47 also includes a recording unit 56 that records oil temperature-density relationship data when the oil temperature drops within a predetermined temperature range, and a coefficient calculation unit 57 that calculates a temperature-dependent coefficient by performing linear regression on the oil temperature-density relationship data recorded in the recording unit 56, and the calculation unit 52 uses the temperature-dependent coefficient to convert the density acquired by the acquisition unit 51 into a density at a predetermined temperature.

[0069] According to this configuration, the density of the oil at a predetermined temperature can be calculated with high accuracy. In addition, the oil change determination notification device 47 is equipped with a measurement sensor 48 that measures the oil density and oil temperature, an acquisition unit 51 acquires the density and oil temperature from the measurement sensor 48, and a calculation unit 52 calculates the density at the oil temperature obtained from the measurement sensor 48 to the density at a predetermined temperature. According to this configuration, it is possible to more appropriately determine when the oil needs to be changed and to notify the driver that the oil needs to be changed. The work machine 1 of this embodiment is a work machine 1 equipped with an oil change determination notification device 47 and a gear-type transmission 18, and the oil also serves as lubricating oil for the gear-type transmission 18.

[0070] According to this configuration, it is possible to appropriately determine and notify when the oil needs to be changed in a work machine 1 in which the lubricating oil for the gear-type transmission 18 is also used as the oil for operating the hydraulic drive unit. The work machine 1 also includes a hydrostatic continuously variable transmission 16, a supply line 37 that supplies oil to a charge circuit 36 ​​of the hydrostatic continuously variable transmission 16, an oil filter 38 provided in the supply line 37, and a measurement sensor 48 that measures at least one of the oil density and oil temperature acquired by the acquisition unit 51, and the measurement sensor 48 measures the oil flowing upstream or downstream of the oil filter 38 in the supply line 37.

[0071] This configuration allows for stable oil measurement and constant oil monitoring. . The work machine 1 also includes a hydrostatic continuously variable transmission 16, a supply line 37 that supplies oil to a charge circuit 36 ​​of the hydrostatic continuously variable transmission 16, a return line 39 through which oil returns from the supply line 37, an oil cooler 41 provided in the return line 39, and a measurement sensor 48 that measures at least the oil density or oil temperature acquired by the acquisition unit 51, and the measurement sensor 48 measures the oil flowing upstream or downstream of the oil cooler 41 in the return line 39.

[0072] This configuration also allows for stable oil measurement and constant monitoring of the oil. The work machine 1 also includes steerable wheels (front wheels 4), a steering cylinder 24 that steers the steerable wheels 4, a hydraulic controller 25 that receives oil and operates the steering cylinder 24, and a measurement sensor 48 that measures at least the oil density or oil temperature acquired by the acquisition unit 51, and the measurement sensor 48 may be configured to measure the oil supplied to the hydraulic controller or the oil returning from the hydraulic controller 25.

[0073] The work machine 1 also includes a vehicle body 2, a lifting cylinder 44 that raises and lowers an implement attached to the vehicle body 2, a lifting control valve 45 that receives oil and controls the lifting cylinder 44, and a measurement sensor 48 that measures at least the oil density or oil temperature acquired by the acquisition unit 51, and the measurement sensor 48 may be configured to measure the oil discharged from the lifting control valve 45, the oil supplied to the lifting control valve 45, or the oil returning from the lifting cylinder 44.

[0074] Although one embodiment of the present invention has been described above, the embodiment disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0075] 1. Work machinery 2. Body 4 Steering wheel (front wheel) 16 Hydrostatic continuously variable transmission 18 gear transmission 24 Steering cylinder 25 Hydraulic Controller 36 Charge Circuit 37 Supply pipeline 38 Oil filter 39 Return Pipe 41 Oil cooler 44 Lifting cylinder 45 Lift control valve 47 Oil change notification device 48 Measurement Sensors 50 Alarm device 51 Acquisition Department 52 Arithmetic section 54 Judgment section 56 Recording Section 57 Coefficient calculation section 58 Lower Threshold 61 Upper Threshold 78 Upper Threshold 76 Variance calculation section

Claims

1. An oil change determination and notification device that determines and notifies the timing of changing oil that operates a hydraulic drive device, an acquisition unit that acquires the density and oil temperature of the oil; a calculation unit that calculates the density acquired by the acquisition unit into a density at a predetermined oil temperature; a determination unit that determines when the oil should be changed based on the density calculated by the calculation unit; a variance calculation unit that calculates the variance of the density calculated by the calculation unit; an alarm device that notifies the driver that it is time to change the oil when the determination unit determines that it is time to change the oil; Equipped with The oil change determination and notification device is configured such that, when the density variance calculated by the variance calculation unit exceeds a preset upper threshold, the determination unit determines that there is a deterioration in antifoaming performance or an increase in contamination, and determines that it is time to change the oil.

2. the determination unit determines that air bubbles have been mixed into the oil when the density calculated by the calculation unit is below a preset lower limit threshold, 2. The oil change determination notification device according to claim 1, wherein, when the determination unit determines that air bubbles have been mixed into the oil, the notification device notifies the user that air bubbles have been mixed into the oil and suggests machine maintenance.

3. 2. The oil change notification device according to claim 1, wherein the determination unit quantitatively evaluates the density of the oil based on the density calculated by the calculation unit to determine when the oil should be changed and the reason for changing the oil.

4. the determination unit determines that the oil has oxidized and / or that contaminants have increased in the oil when the density calculated by the calculation unit exceeds a preset upper threshold, and determines that it is time to change the oil; 2. The oil change determination notification device according to claim 1, wherein the notification device notifies the user that the reason for changing the oil is oxidation of the oil and / or an increase in contaminants mixed in the oil, and that it is time to change the oil.

5. 2. The oil change determination and notification device according to claim 1, wherein the notification device notifies the user that the reason for changing the oil is a deterioration in antifoaming performance or an increase in contamination, and that it is time to change the oil.

6. An oil change determination and notification device that determines and notifies when it is time to change the oil that operates a hydraulic drive device, an acquisition unit that acquires the density and oil temperature of the oil; a calculation unit that calculates the density acquired by the acquisition unit into a density at a predetermined oil temperature; a determination unit that determines when the oil should be changed based on the density calculated by the calculation unit; an alarm device that notifies the driver that it is time to change the oil when the determination unit determines that it is time to change the oil; a recording unit that records data on the relationship between oil temperature and density when the oil temperature of the oil drops within a predetermined temperature range; a coefficient calculation unit that calculates a temperature dependency coefficient by performing linear regression on the oil temperature-density relationship data recorded in the recording unit; Equipped with The calculation unit calculates the density acquired by the acquisition unit into a density at the predetermined temperature using the temperature-dependent coefficient.

7. a measurement sensor for measuring the density and temperature of the oil; The acquisition unit acquires density and oil temperature from the measurement sensor, 2. The oil change notification device according to claim 1, wherein the calculation unit calculates the density at the oil temperature obtained from the measurement sensor into the density at the predetermined temperature.

8. A work machine equipped with the oil change determination notification device and a gear-type transmission according to claim 1, The oil also serves as a lubricating oil for the gear-type transmission.

9. A hydrostatic continuously variable transmission; a supply line for supplying the oil to a charge circuit of the hydrostatic continuously variable transmission; an oil filter provided in the supply line; a measurement sensor that measures at least one of the oil density and the oil temperature acquired by the acquisition unit; Equipped with The work machine according to claim 8 , wherein the measurement sensor measures the oil flowing in the supply pipe line upstream or downstream of the oil filter.

10. A hydrostatic continuously variable transmission; a supply line for supplying the oil to a charge circuit of the hydrostatic continuously variable transmission; a return line through which the oil returning from the supply line flows; an oil cooler provided in the return pipe; a measurement sensor that measures at least one of the oil density and the oil temperature acquired by the acquisition unit; Equipped with The work machine according to claim 8 , wherein the measurement sensor measures oil flowing in the return pipe line upstream or downstream of the oil cooler.

11. A steering wheel and a steering cylinder for steering the steered wheels; a hydraulic controller that receives the oil and operates the steering cylinder; a measurement sensor that measures at least one of the oil density and the oil temperature acquired by the acquisition unit; Equipped with The work machine according to claim 8 , wherein the measurement sensor measures oil supplied to the hydraulic controller or oil returned from the hydraulic controller.

12. The car body and a lifting cylinder for lifting and lowering an implement attached to the vehicle body; a lift control valve to which the oil is supplied and which controls the lift cylinder; a measurement sensor that measures at least one of the oil density and the oil temperature acquired by the acquisition unit; Equipped with The work machine according to claim 8 , wherein the measurement sensor measures oil discharged from the lift control valve, oil supplied to the lift control valve, or oil returning from the lift cylinder.

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