Oil condition estimation device and oil condition estimation method

Abstract

An oil condition estimation device (30) comprising: a first sensing unit (321) that detects a pressure (P) of oil (E) stored in an oil pan (10) from a pressure sensor (12) provided on a bottom surface (B) of the oil pan (10) of an internal combustion engine; a second sensing unit (322) that detects a distance (H) between the bottom surface (B) and a liquid level (T) of the oil (E) from a level sensor (13) provided in the oil pan (10); and a calculation unit (324) that calculates a density (λ) of the oil (E) based on the pressure (P) and the distance (H).

Description

Technical field

[0001] The present disclosure relates to an oil condition estimation device and an oil condition estimation method. State of the art

[0002] A conventional oil tester detects that oil has deteriorated when the propagation speed of ultrasonic waves sent through the oil placed in an oil tank for measurement is low (for example, JP H09 127067 A). Brief description of the invention [Problem to be solved by the invention]

[0003] When measuring oil density with a conventional oil tester, it is necessary to transfer oil from a device such as an engine to the oil tank for measurement before measuring the propagation speed of ultrasonic waves, which increases the effort required for the measurement. Furthermore, since the transducer for generating ultrasonic waves is expensive, the costs for such measurements increase.

[0004] The present disclosure was made with these points in mind, and its purpose is to estimate the density of oil in a simple and cost-effective manner. MEANS TO SOLVENT THE PROBLEM

[0005] An oil condition estimation device according to a first aspect of the present disclosure comprises: a first sensing unit that detects a pressure of oil stored in an oil pan from a pressure sensor provided on a bottom surface of the oil pan of an internal combustion engine; a second sensing unit that detects a distance between the bottom surface and a liquid level of the oil from a level sensor provided in the oil pan; and a calculation unit that calculates a density of the oil based on the pressure and the distance.

[0006] The oil condition estimation device may further include: an estimation unit that estimates that the condition of the oil is abnormal if a density difference, representing a difference between a first density calculated by the estimation unit at a first time point in time and a second density calculated by the estimation unit at a second time point in time after the first time point in time, is equal to or greater than a threshold value.

[0007] The estimation unit can estimate that the oil has deteriorated if the density difference is equal to or greater than the threshold and the first density is less than the second density.

[0008] The estimation unit can estimate that the oil has been diluted by fuel injected into the internal combustion engine if the density difference is equal to or greater than the threshold and the first density is greater than the second density.

[0009] The greater the distance traveled by a moving body equipped with an internal combustion engine after the oil stored in the oil pan has been changed, the more the estimation unit can reduce the threshold.

[0010] The calculation unit can calculate the initial density by detecting a change in the oil stored in the oil pan.

[0011] The computation unit can calculate, as the second density, a statistical quantity of a multitude of second densities, which are calculated for each predetermined first cycle in a second cycle that is longer than the first cycle.

[0012] The calculation unit can calculate at least one of the first density or the second density within a period from a time at which a process to start the internal combustion engine is received until a time immediately before the internal combustion engine starts.

[0013] The oil condition estimation device may further include: a notification unit that notifies a user of the internal combustion engine that the estimation unit has estimated that the condition of the oil is abnormal.

[0014] The notification unit can cause a display device to show a first warning image if the estimation unit estimates that the oil has deteriorated, and cause the display device to show a second warning image if the estimation unit estimates that the oil has been diluted.

[0015] The calculation unit can calculate a weight of the oil based on the pressure of the oil and a cross-sectional area of ​​the oil pan corresponding to a position of the fluid level of the oil, and the oil condition estimation device can further include an estimation unit that estimates that a malfunction has occurred in the internal combustion engine when a subtraction value obtained by subtracting a second weight of the oil, calculated by the calculation unit at a second time point after a first time point, from a first weight of the oil, calculated by the calculation unit at the first time point, is equal to or greater than a threshold value.

[0016] The calculation unit can calculate the weight of the oil within a period from a point in time at which a predetermined time has elapsed after the combustion engine has stopped, up to a point in time immediately before the combustion engine starts.

[0017] The oil condition estimation device may further include: a notification unit that notifies a user of the internal combustion engine that the estimation unit has estimated that a malfunction has occurred in the internal combustion engine.

[0018] An oil condition estimation method according to a second aspect of the present disclosure comprises: a first detection step of detecting a pressure of oil stored in an oil pan from a pressure sensor provided on a bottom surface of the oil pan of the internal combustion engine; a second detection step of detecting a distance between the bottom surface and a liquid level of the oil from a level sensor provided in the oil pan; and a calculation step of calculating a density of the oil based on the pressure and the distance. IMPACT OF THE INVENTION

[0019] According to the present disclosure, it is possible to estimate the density of oil in a simple and cost-effective manner. Brief description of the drawings Fig. Figure 1 shows an overview of an oil condition estimation system S according to the present embodiment. Fig. Figure 2 shows the process of estimating an anomaly in the state of oil E. Fig. Figure 3 shows the process of estimating a malfunction of an internal combustion engine. Description of the embodiments<Overview of an oil condition estimation system S>

[0020] Fig. Figure 1 shows an overview of an oil condition estimation system S according to the present embodiment. The in Fig. The oil condition estimation system S shown in Figure 1 comprises an oil pan 10, a strainer 11, a pressure sensor 12, a level sensor 13, a control unit 20, a display device 21, an audio output device 22, and an oil condition estimation device 30. The oil condition estimation system S has the function of estimating, based on the density ρ of oil E, whether the condition of oil E in an internal combustion engine is abnormal or not, and of notifying a user of the internal combustion engine if the condition of oil E is estimated to be abnormal. The abnormality in the condition of oil E could be, for example, deterioration of oil E or dilution of oil E by fuel. The user could be, for example, the driver of a moving body if the internal combustion engine is mounted in a moving body such as a vehicle.

[0021] The oil pan 10 is a tank located in a lower part of the internal combustion engine and stores oil E that circulates within the engine. The strainer 11 is located at the distal end of an intake port of an oil pump (not shown), which draws in oil E stored in the oil pan 10 and supplies it to the internal combustion engine. The strainer 11 acts as a filter for filtering the oil E. The pressure sensor 12 is a sensor located on a bottom surface B of the oil pan 10 and detects the pressure of the oil E stored in the oil pan 10. The level sensor 13 is a sensor located in the oil pan 10 and detects the distance H between the bottom surface B of the oil pan 10 and the fluid level T of oil E.

[0022] The control unit 20 is a device containing a processor, such as a central processing unit (CPU) or an electronic control unit (ECU), and controls the operation of the internal combustion engine. For example, the control unit 20 starts or stops the internal combustion engine in response to an operation performed by a user. The display device 21 is, for example, a display. The audio output device 22 is a loudspeaker.

[0023] The oil condition estimator 30 calculates the density p of oil E based on the pressure P of oil E detected by the pressure sensor 12 and the distance H detected by the level sensor 13. This operation allows the oil condition estimator 30 to easily calculate the density ρ without transferring oil E to a container outside the oil sump 10. Furthermore, since the oil condition estimator 30 calculates the density p without using ultrasonic waves generated by a transducer, the density p can be calculated more cost-effectively. Based on the calculated density p, the oil condition estimator 30 estimates whether the condition of oil E is abnormal and notifies the user if it estimates that oil E is abnormal. <Aufbau der Ölzustandsschätzungsvorrichtung 30>

[0024] As in Fig. As shown in Figure 1, the oil condition estimation device 30 comprises a storage unit 31 and a control unit 32. The control unit 32 comprises a first sensing unit 321, a second sensing unit 322, a third sensing unit 323, a calculation unit 324, an estimation unit 325 and a notification unit 326.

[0025] The memory unit 31 includes, for example, a storage medium such as read-only memory (ROM), random-access memory (RAM), a hard disk drive (HDD), or a solid-state drive (SSD). The memory unit 31 stores programs executed by the control unit 32 and various types of information so that the oil condition estimation device 30 can estimate the condition of oil E.

[0026] The control unit 32 is a processor such as a CPU or an ECU. The control unit 32 functions as the first acquisition unit 321, the second acquisition unit 322, the third acquisition unit 323, the calculation unit 324, the estimation unit 325, and the notification unit 326 by executing the programs stored in the memory unit 31. It should be noted that the control unit 32 can be configured by a single processor, by a plurality of processors, or by a combination of one or more processors and an electronic circuit.

[0027] The first sensing unit 321 detects the pressure P of oil E, which is stored in the oil pan 10, from the pressure sensor 12, which is provided on the bottom surface B of the oil pan 10 of the internal combustion engine. The second sensing unit 322 detects the distance H (position of the liquid level T) between the bottom surface B and the liquid level T of oil E from the level sensor 13, which is provided in the oil pan 10.

[0028] The third sensing unit 323 acquires various types of information from the controller 20. For example, the third sensing unit 323 acquires change information from the controller 20, indicating that oil E has been replaced by new oil E. By acquiring this change information, the computation unit 324 can calculate the density ρ of oil E immediately after the change to new oil E. If the internal combustion engine is mounted in a moving body, such as a vehicle, the third sensing unit 323 can acquire distance information, indicating the distance traveled by the moving body, or time information, indicating the travel time of the moving body, instead of change information.By capturing the distance or time information, the calculation unit 324 can estimate the time at which oil E was replaced by new oil E, based on the distance traveled or travel time of the moving body, and calculate the density p at that time.

[0029] For example, the third acquisition unit 323 receives time information from the controller 20 indicating (i) a start time at which the internal combustion engine is started, or (ii) a stop time at which the internal combustion engine is stopped. The start time is, for example, the time at which the operation to start the internal combustion engine is received from the user of the internal combustion engine. The stop time is, for example, the time immediately after the piston stops. By acquiring the time information, the computation unit 324 can calculate the density p at a suitable time.

[0030] The calculation unit 324 calculates the density p of oil E based on the pressure P measured by the first detection unit 321 and the distance H measured by the second detection unit 322. The density p can be expressed by equation 1 using the pressure P and the distance H. The constant g represents the acceleration due to gravity (9.80665 m / s²). 2 ) dar. ρ=PgH

[0031] This operation allows the computational unit 324 to calculate the density ρ of oil E without transferring oil E from the oil pan 10 to the external container. Furthermore, the computational unit 324 can calculate the density p without using an oil sensor equipped with a vibrator.

[0032] The computation unit 324 calculates an initial density (hereinafter referred to as "density ρ1") of oil E by detecting the change of oil E stored in the oil pan 10. For example, the computation unit 324 detects the change of oil E because the third detection unit 323 detects the change information and calculates the density ρ1. The computation unit 324 can calculate the density ρ1 if the difference between (i) a distance included in the distance information detected by the third detection unit at the present time and (ii) a distance included in the distance information detected at a time prior to the present time is equal to or greater than a predetermined distance.The computation unit 324 can calculate the density ρ1 if the difference between (i) a travel time contained in the time information recorded by the third acquisition unit at the present time, and (ii) a travel time contained in the time information recorded at a time prior to the present time, is equal to or greater than a predetermined time.

[0033] The computational unit 324 calculates a second density (hereinafter referred to as "density ρ2") of oil E in a predetermined first cycle, starting from the point in time at which the density ρ1 was calculated. The predetermined first cycle is, for example, one day. The computational unit 324 can calculate, as density p2, a statistical value from a multitude of densities p2 calculated for each first cycle in a second cycle that is longer than the predetermined first cycle. If the first cycle is one day, the second cycle is, for example, one week. The statistical value is, for example, an average or a median value. Through this operation, the computational unit 324 can use the statistical value, based on the multitude of densities p2 calculated at multiple points in time, as the density p2. Therefore, it is possible to improve the accuracy of the density p2 calculation.

[0034] If the internal combustion engine is mounted in a moving body such as a vehicle, and the moving body travels on an uneven road or suddenly accelerates or decelerates, the height T of the fluid level of oil E (the distance H between the ground surface B and the fluid level T) or the slope of the fluid level T changes, and therefore the accuracy of the calculation of the density ρ of oil E can decrease. Therefore, the calculation unit 324 can calculate at least one of the densities ρ1 or ρ2 within a period from the time the operator to start the internal combustion engine is received until a time immediately before the internal combustion engine starts.

[0035] For example, after the third sensing unit 323 has acquired the time information indicating the start time, the computation unit 324 instructs the first sensing unit 321 to acquire the pressure P of oil E and the second sensing unit 322 to acquire the distance H. The computation unit 324 then calculates the density ρ of oil E based on the acquired pressure P and distance H. Since the internal combustion engine is started with a starter motor after receiving the start command, the computation unit 324 can calculate the density p while the starter motor is operating (i.e., before the internal combustion engine starts) by operating as described above. Consequently, the computation unit 324 can calculate the density p before the moving body begins to move, thus improving the accuracy of the density ρ calculation.

[0036] The calculation unit 324 can calculate not only the density ρ of oil E, but also the weight W of oil E stored in oil pan 10. For example, the calculation unit 324 calculates the weight W of oil E based on the pressure P of oil E and a cross-sectional area A of oil pan 10, which corresponds to the position T of the liquid level of oil E. The cross-sectional area A is stored in storage unit 31. The weight W can be expressed by equation 2 using the distance H, the cross-sectional area A, and the density ρ. Then, the weight W can be expressed by equation 3 using equations 1 and 2. W=ρHA W=PAg

[0037] Through this operation, the calculation unit 324 enables the estimation unit 325 to estimate the condition of the internal combustion engine (for example, the presence or absence of a malfunction) on the basis of the weight W.

[0038] While the internal combustion engine is running, oil E circulates within it. Consequently, the weight W of oil E stored in oil pan 10 is less than the weight W of oil E while the engine is stopped. Furthermore, since some of the oil E adheres to various parts of the engine immediately after it stops, its weight W cannot be calculated precisely. Therefore, the calculation unit 324 can calculate the weight W of oil E over a period from the point at which a predetermined time has elapsed since the engine stopped until just before the engine starts. The predetermined time is, for example, 3 hours.

[0039] For example, the calculation unit 324 detects that the predetermined time has elapsed since the third detection unit 323 recorded the time information indicating the stop time, and that the third detection unit 323 has not yet recorded the time information indicating the start time. The calculation unit 324 then prompts the first detection unit 321 to record the pressure P at the time of this detection and calculates the weight W using the pressure P. Through the operation described above, the calculation unit 324 can improve the accuracy of the calculation of the weight W of oil E.

[0040] The cross-sectional area A of the oil pan 10 can vary depending on its distance from the base surface B. Therefore, the computation unit 324 can identify the cross-sectional area A corresponding to the distance H detected by the second detection unit 322 and calculate the weight W based on the identified cross-sectional area A and the pressure P. For example, the computation unit 324 identifies the cross-sectional area A corresponding to the distance H by referring to a cross-sectional area table stored in the storage unit 31 and then calculates the weight W. The cross-sectional area A contained in the cross-sectional area table stored in the storage unit 31 is, for example, a quotient obtained by dividing the volume of the oil pan 10 corresponding to each vertical distance from the base surface B by that distance.Through the operation described above, the calculation unit 324 can calculate the weight W of oil E with high accuracy, regardless of the shape of the oil pan 10.

[0041] If the density difference, which represents the difference between the density ρ1 calculated by the computation unit 324 at a first time point and the density ρ2 calculated by the computation unit 324 at a second time point after the first time point, is equal to or greater than a first threshold, the estimation unit 325 estimates that the condition of oil E is abnormal. The first time point is a time point at which the change of oil E stored in the oil pan 10 is detected, and the second time point is a time point that occurs in each predetermined cycle after the time point at which the density ρ1 was calculated. The first threshold can be a fixed value stored in the storage unit 31 or a predetermined ratio (for example, 10%) of the density ρ1.

[0042] For example, in a case where the density difference is equal to or greater than the first threshold and the density ρ1 is less than the density ρ2, the estimation unit 325 estimates that a substance contained in oil E has evaporated or that oil E has deteriorated due to oxidation. For example, in a case where the density difference is equal to or greater than the first threshold and the density ρ1 is greater than the density ρ2, the estimation unit 325 estimates that oil E has been diluted by the fuel injected into the internal combustion engine. Through the operation described above, the estimation unit 325 can estimate the type of anomaly in the condition of oil E.

[0043] The greater the distance traveled by the internal combustion engine-equipped vehicle after the oil E stored in oil pan 10 has been changed, the more the estimation unit 325 can reduce the initial threshold. The more time that has elapsed since the oil E stored in oil pan 10 was changed, the more the estimation unit 325 can reduce the initial threshold. This operation allows the estimation unit 325 to more easily estimate that the condition of oil E is abnormal as the distance or the time elapsed since the oil change of oil E increases, thus making it easier to prompt the driver to change the oil E.

[0044] The estimation unit 325 can estimate that a malfunction has occurred in the internal combustion engine if the subtraction value obtained by subtracting a second weight of oil E, calculated by the calculation unit 324 at the second time point (after the first time point), from a first weight of oil E, calculated by the calculation unit 324 at the first time point, is equal to or greater than a second threshold value. The second threshold value can be a fixed value stored in the storage unit 31 or a predetermined ratio (for example, 10%) of the first weight. Through this operation, the estimation unit 325 can estimate whether oil E is being consumed due to a malfunction of the internal combustion engine. In the following description, the first weight is referred to as "weight W1" and the second weight as "weight W2".

[0045] The notification unit 326 notifies the driver of the estimate result by causing the display device 21 to show a warning image corresponding to an estimate result provided by the estimation unit 325, or by causing the audio output device 22 to emit a warning tone corresponding to the estimate result. For example, the notification unit 326 notifies the internal combustion engine user that the estimation unit 325 has estimated that the condition of oil E is abnormal because the density difference is equal to or greater than the first threshold. The notification unit 326 can cause the display device 21 to show a first warning image if the estimation unit 325 estimates that oil E has deteriorated, and it can cause the display device to show a second warning image if the estimation unit 325 estimates that oil E has been diluted.

[0046] The notification unit 326 notifies the user of the internal combustion engine that the estimation unit 325 has estimated that a malfunction has occurred in the internal combustion engine, for example, based on the weight of oil E. In this case, the notification unit 326 causes the display device 21 to display, for example, a third warning image corresponding to the malfunction of the internal combustion engine. By operating in this way, the notification unit 326 enables the user of the internal combustion engine to easily ascertain the condition of the oil E and the condition of the internal combustion engine. <Verarbeitungsablauf in der Ölzustandsschätzungsvorrichtung 30>

[0047] Fig. 2 and Fig. Figure 3 each represents a diagram illustrating an example of a processing sequence in the oil condition estimation device 30. Fig. Figure 2 shows the process of estimating an anomaly in the state of oil E, and Fig. Figure 3 shows the process of estimating a malfunction of the internal combustion engine.

[0048] First, the process of estimating an anomaly in the state of oil E is described. As in Fig. As shown in Figure 2, the calculation unit 324 detects whether oil E has been changed, based on whether the third detection unit 323 has recorded the change information (S11). If no oil change is detected (NO in S11), the calculation unit 324 repeats the process from step S11. If an oil change is detected (YES in S11), the calculation unit 324 determines whether the user of the internal combustion engine has performed the process of starting the internal combustion engine, based on the time information recorded by the third detection unit 323 (S12).

[0049] If the third detection unit 323 has not detected the time information indicating the start time (NO in S12), in other words, if it is determined that the user of the internal combustion engine did not perform the operation to start the engine, the calculation unit 324 repeats the process from step S12. If the third detection unit 323 has detected the time information (YES in S12), in other words, if it is determined that the user of the internal combustion engine did perform the operation to start the engine, the calculation unit 324 calculates the density p1 (S13). If the predetermined cycle has not elapsed after the calculation of the density p1 (NO in S14), the calculation unit 324 detects whether or not oil E has been changed again (S15).If an oil change is detected (YES in S15), the calculation unit 324 returns to the process of step S12, and if no oil change is detected (NO in S15), the calculation unit 324 returns to the process of step S14.

[0050] If the predetermined cycle has elapsed after the density p1 calculation (YES in S14), the calculation unit 324 determines whether the user has performed the operation to start the internal combustion engine (S16). If the third detection unit 323 has not detected the time information indicating the start time (NO in S16), in other words, if it is determined that the user of the internal combustion engine has not performed the operation to start the internal combustion engine, the calculation unit 324 repeats the process from step S16.When the third acquisition unit 323 acquires the time information (JA in S16), in other words, in a case where it is determined that the user of the internal combustion engine has performed the process of starting the internal combustion engine, the calculation unit 324 calculates the density ρ2 (S17) and the estimation unit 325 calculates the absolute value D of the difference between the density ρ1 and the density ρ2 (S18).

[0051] If the absolute value D is less than the first threshold (NO in S19), the calculation unit 324 returns to the process from step S14. If the absolute value is equal to or greater than the first threshold (YES in S19) and the density ρ1 is greater than the density ρ2 (YES in S20), the estimation unit 325 estimates that oil E has been diluted by fuel (S21). Then, the notification unit 326 notifies the user that the estimation unit 325 has estimated that oil E has been diluted by fuel (S23).

[0052] If the absolute value is equal to or greater than the first threshold (YES in S19) and the density ρ1 is less than the density ρ2 (NO in S20), the estimating unit 325 estimates that oil E has deteriorated (S22). The notification unit 326 then notifies the user that the estimating unit 325 has estimated that oil E has deteriorated (S23). If the instruction to stop the process is not received (NO in S24), the oil condition estimating device 30 returns to the process from step S11. If an instruction to stop the process is received (YES in S24), the oil condition estimating device 30 terminates the process.

[0053] Next, the process of estimating the malfunction of the internal combustion engine is described. As in Fig.As shown in Figure 3, the processing unit 324 determines whether the user has performed the operation to stop the internal combustion engine, based on the time information (S31) captured by the third sensing unit 323. If the third sensing unit 323 has not captured the time information indicating the stop time (NO in S31), in other words, if it is determined that the user of the internal combustion engine has not performed the operation to start the internal combustion engine, the processing unit 324 repeats the process from S31. If the third sensing unit 323 has captured the time information (YES in S31), in other words, if it is determined that the user of the internal combustion engine has performed the operation to start the internal combustion engine, the processing unit 324 determines whether the predetermined time has elapsed or not (S32).

[0054] If the predetermined time has not elapsed (NO in S32), the computation unit 324 repeats the process from step S32. If the predetermined time has elapsed (YES in S32), the computation unit 324 determines whether the current time is before or after the time at which the operation to start the internal combustion engine was performed, based on the time information (S33) acquired by the third acquisition unit 323. If the third acquisition unit 323 acquires the time information indicating the start time, the computation unit 324 determines that the current time is after the time at which the operation to start the internal combustion engine was performed (NO in S33) and returns to the process from step S31.If the third acquisition unit 323 has not acquired the time information, the calculation unit 324 determines that the present time is before the time at which the process to start the internal combustion engine is carried out (JA in S33), and calculates the weight W2 of oil E (S34).

[0055] Estimation unit 325 retrieves the weight W1 of oil E, calculated by calculation unit 324 at the previous time (for example, the time at which calculation unit 324 detects an oil change), by accessing storage unit 31 (S35), and calculates the subtraction value V, obtained by subtracting weight W2 from weight W1 (S36). If the subtraction value V is less than the second threshold (NO in S37), estimation unit 325 estimates that no malfunction has occurred in the internal combustion engine (S39) and returns to the process from step S31. If the subtraction value V is equal to or greater than the second threshold (YES in S37), estimation unit 325 estimates that a malfunction has occurred in the internal combustion engine (S38). Notification unit 326 then notifies the user that a malfunction has occurred in the internal combustion engine (S40). <Wirkungen der Ölzustandsschätzungsvorrichtung 30>

[0056] As described above, the oil condition estimation device 30 comprises the first sensing unit 321, which detects the pressure P of oil E stored in the oil pan 10 from the pressure sensor 12, which is provided on the bottom surface B of the oil pan 10 of the internal combustion engine, the second sensing unit 322, which detects the distance H between the bottom surface B and the liquid level T of oil E from the level sensor 13, which is provided in the oil pan 10, and the calculation unit 324, which calculates the density ρ of oil E on the basis of the pressure P and the distance H.

[0057] Since the oil condition estimator 30 is configured in this way, it can estimate the density of oil E with high accuracy without transferring oil E from the oil pan 10 to the external container. Furthermore, the oil condition estimator 30 can estimate the density of oil E with high accuracy without using an oil sensor equipped with a vibrator. Consequently, the oil condition estimator 30 can estimate the density of oil E in a simple and cost-effective manner with high accuracy.

[0058] The present disclosure is explained on the basis of the exemplary embodiments. The technical scope of protection of the present disclosure is not limited to the scope explained in the embodiments above, and it is possible to make various changes and modifications within the scope of the disclosure. For example, the entire device or a part thereof can be configured with any unit that is functionally or physically distributed or integrated. Furthermore, new exemplary embodiments generated by any combination thereof are included in the exemplary embodiments. Moreover, the effects of the new exemplary embodiments achieved by the combinations also have the effects of the original exemplary embodiments. [List of reference symbols] S Oil Condition Estimation System 10 Oil pan 11 sieve 12 Pressure sensor 13 Level sensor 20 Control 21 Display device 22 Audio output device 30 Oil condition estimation device 31 storage units 32 Control unit 321 First recording unit 322 Second recording unit 323 Third recording unit 324 units of calculation 325 Estimate Unit 326 notification unit

Claims

[1] Oil condition estimation device (30), comprising: a first detection unit (321) which detects a pressure (P) of oil (E) stored in an oil pan (10) from a pressure sensor (12) provided on a bottom surface (B) of the oil pan (10) of an internal combustion engine; a second detection unit (322) that detects a distance (H) between the bottom surface (B) and a liquid level (T) of the oil (E) from a level sensor (13) provided in the oil pan (10); and a calculation unit (324) that calculates a density (p) of the oil (E) based on the pressure (P) and the distance (H). [2] Oil condition estimation device (30) according to claim 1, further comprising: an estimation unit (325) that estimates that a condition of the oil (E) is abnormal if a density difference, which is a difference between a first density (ρ1) calculated by the estimation unit (324) at a first time point and a second density (p2) calculated by the estimation unit (324) at a second time point after the first time point, is equal to or greater than a threshold value. [3] Oil condition estimation device (30) according to claim 2, wherein the estimation unit (325) estimates that the oil (E) has deteriorated if the density difference is equal to or greater than the threshold and the first density (p1) is less than the second density (p2). [4] Oil condition estimation device (30) according to claim 2 or 3, wherein the estimation unit (325) estimates that the oil (E) has been diluted by fuel injected into the internal combustion engine if the density difference is equal to or greater than the threshold and the first density (p1) is greater than the second density (p2). [5] Oil condition estimation device (30) according to one of claims 2 to 4, wherein, the greater the distance traveled by a moving body equipped with the internal combustion engine after the oil (E) stored in the oil pan (10) has been changed, the more the estimation unit (325) reduces the threshold value. [6] Oil condition estimation device (30) according to one of claims 2 to 5, wherein the calculation unit (324) calculates the first density (p1) by detecting a change in the oil (E) stored in the oil pan (10). [7] Oil condition estimation device (30) according to one of claims 2 to 6, wherein the calculation unit (324) calculates as the second density (p2) a statistical quantity of a plurality of second densities (p2) that are calculated for each predetermined first cycle in a second cycle that is longer than the first cycle. [8] Oil condition estimation device (30) according to any one of claims 2 to 7, wherein the calculation unit (324) calculates at least one of the first density (p1) or the second density (p2) within a period from a time at which a process to start the internal combustion engine is received until a time immediately before the internal combustion engine starts. [9] Oil condition estimation device (30) according to any one of claims 2 to 8, further comprising: a notification unit (326) that notifies a user of the internal combustion engine that the estimation unit (325) has estimated that the condition of the oil (E) is abnormal. [10] Oil condition estimation device (30) according to claim 9, wherein the notification unit (326) causes a display device (21) to display a first warning image when the estimation unit (325) estimates that the oil (E) has deteriorated, and the display device (21) causes the display device (21) to display a second warning image when the estimation unit (325) estimates that the oil (E) has been diluted. [11] Oil condition estimation device (30) according to any one of claims 1 to 10, wherein the calculation unit (324) calculates a weight of the oil (E) based on the pressure (P) of the oil (E) and a cross-sectional area (A) of the oil pan (10) which corresponds to a position of the liquid level (T) of the oil (E), and The oil condition estimation device further comprises an estimation unit (325) which estimates that a malfunction has occurred in the internal combustion engine if a subtraction value obtained by subtracting a second weight (W2) of the oil (E), calculated by the calculation unit (324) at a second time point after a first time point, from a first weight (W1) of the oil (E), calculated by the calculation unit (324) at the first time point, is equal to or greater than a threshold value. [12] Oil condition estimation device (30) according to claim 11, wherein the calculation unit (324) calculates the weight of the oil (E) within a period from a time at which a predetermined time has elapsed after the combustion engine has stopped, to a time immediately before the combustion engine starts. [13] Oil condition estimation device (30) according to claim 11 or 12, further comprising: a notification unit (326) that notifies a user of the internal combustion engine that the estimation unit (325) has estimated that a malfunction has occurred in the internal combustion engine. [14] An oil condition estimation method performed by a processor (32), comprising: a first detection step of detecting a pressure (P) of oil (E) stored in an oil pan (10) by a pressure sensor (12) provided on a bottom surface (B) of the oil pan (10) of the internal combustion engine; a second detection step of detecting a distance (H) between the bottom surface (B) and a liquid level (T) of the oil (E) by a level sensor (13) provided in the oil pan (10); and a calculation step of calculating the density (p) of the oil (E) based on the pressure (P) and the distance (H).

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