JP2022178988A - Oil deterioration estimation device - Google Patents

Abstract

To provide an oil deterioration estimation device capable of estimating deterioration of engine oil of an internal combustion engine by using increase in viscosity of the engine oil due to deterioration with a simple configuration.SOLUTION: An oil deterioration estimation device 100 estimates deterioration of engine oil 2 of an engine 1. The oil deterioration estimation device 100 includes a pump 4 for pressure-feeding the engine oil 2, a throttle 6 provided in the downstream of the pump 4 and the upstream of a lubrication object 5, a pressure difference acquiring section for acquiring a pressure difference between an upstream pressure and a downstream pressure of the throttle 6, and an estimation section for estimating a deterioration degree in correspondence with increase in velocity of the engine oil 2 due to deterioration on the basis of the pressure difference.SELECTED DRAWING: Figure 1

Description

The present invention relates to an oil deterioration estimation device.

2. Description of the Related Art Conventionally, there is known an engine oil deterioration detection device that detects deterioration of engine oil based on an increase in viscosity (see, for example, Patent Document 1).

JP-A-09-317432

In the prior art described above, a pipe whose both ends are communicated with an oil pan, an impeller provided in an enlarged portion in the middle of the pipe, and a motor provided outside the pipe for rotating the shaft of the impeller, Deterioration is detected when the load of the motor exceeds a specific value based on the measurement result of the load measuring unit connected to the motor. In such a configuration, in addition to the existing oil passage, it is necessary to add a separate pipe for installing the impeller to the oil pan. In addition, for example, since the supporting portion of the shaft of the impeller installed inside the pipe of the separate path is required to be oil-tight, the sealing structure becomes complicated and precise.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an oil deterioration estimating apparatus capable of estimating the deterioration of engine oil in an internal combustion engine by utilizing the viscosity increase of engine oil due to deterioration with a simple configuration.

An oil deterioration estimating device according to one aspect of the present invention is an oil deterioration estimating device for estimating deterioration of engine oil of an internal combustion engine, comprising: a pump for pumping engine oil to an oil passage; A throttle section provided upstream from the target, a differential pressure acquisition section that acquires the differential pressure between the upstream pressure and the downstream pressure of the throttle section, and deterioration corresponding to an increase in engine oil viscosity due to deterioration based on the differential pressure. an estimating unit for estimating the degree.

In the oil deterioration estimating device according to one aspect of the present invention, the throttle section is provided downstream of the pump that pumps the engine oil in the oil passage and upstream of the object to be lubricated. At this throttle portion, pressure loss occurs in the engine oil flowing through the oil passage. The degree of this pressure loss increases as the viscosity of the engine oil increases. That is, as the viscosity of the engine oil increases due to deterioration, the pressure loss of the engine oil at the throttle portion increases. Therefore, the degree of pressure loss of the engine oil can be estimated by the estimating section based on the differential pressure between the upstream pressure and the downstream pressure of the throttle section. Therefore, according to this oil deterioration estimating device, it is possible to estimate the deterioration of the engine oil of the internal combustion engine by utilizing the viscosity increase of the engine oil due to deterioration with a simple configuration.

In one embodiment, the oil deterioration estimating device further includes an oil temperature acquisition unit that acquires the temperature of the engine oil, and a rotation speed acquisition unit that acquires the rotation speed of the internal combustion engine. , and the number of revolutions, it may be determined that the engine oil has deteriorated when the differential pressure is equal to or greater than a predetermined first threshold. In this case, the degree of deterioration of the engine oil can be estimated from the degree of increase in the differential pressure by utilizing the fact that the relationship between the degree of increase in the differential pressure and the degree of deterioration of the engine oil can be arranged for each temperature and rotation speed.

In one embodiment, the oil deterioration estimating device further includes an estimated viscosity calculating section that estimates an increase in viscosity based on the differential pressure, and the estimating section is configured such that the viscosity increase estimated by the estimated viscosity calculating section It may be determined that the engine oil has deteriorated when it is equal to or greater than two thresholds. In this case, the degree of increase in viscosity can be estimated from the degree of increase in differential pressure by using the previously obtained relationship between the degree of increase in viscosity of engine oil and the degree of increase in differential pressure. The degree of deterioration of the engine oil can be estimated based on the fact that the degree of viscosity increase exceeds a certain level.

In one embodiment, the oil deterioration estimating device includes a heater that can heat engine oil, and when the increase in viscosity estimated by the estimating unit is equal to or greater than a predetermined third threshold that is smaller than the second threshold, and a heater control unit that controls the heater to heat the engine oil. In this case, the viscosity may increase at low temperatures rather than deterioration, such as during start-up in a low temperature environment. Therefore, by heating the engine oil with a heater, the viscosity of the engine oil can be reduced and the startability can be improved.

In one embodiment, the oil deterioration estimating device may further include an engine control unit that limits the operation of the engine when the estimating unit determines that the engine oil has deteriorated. In this case, there is a possibility that the protection performance of the engine oil has deteriorated due to deterioration. Therefore, the engine can be protected by restricting the operation of the engine.

According to the present invention, it is possible to estimate the deterioration of engine oil in an internal combustion engine by utilizing the increase in viscosity of engine oil due to deterioration with a simple configuration.

1 is a schematic diagram showing the configuration of an oil deterioration estimating device according to a first embodiment; FIG. FIG. 2 is a diagram showing a functional configuration of the oil deterioration estimating device of FIG. 1; FIG. 4 is a diagram for explaining an increase in viscosity of upstream pressure due to deterioration; FIG. 4 is a diagram for explaining an increase in viscosity of downstream pressure due to deterioration; FIG. 4 is a diagram for explaining calculation of an increase in estimated viscosity; FIG. It is a figure for demonstrating a 1st deterioration determination. It is a figure for demonstrating heater heating determination. 6 is a flow chart showing an example of a first deterioration determination process; It is a flow chart which shows an example of heater heating processing. It is a figure for demonstrating a 2nd deterioration determination. 9 is a flowchart showing an example of second deterioration determination processing; It is a schematic diagram showing the configuration of an oil deterioration estimation device of a second embodiment. FIG. 13 is a diagram showing a functional configuration of the oil deterioration estimation device of FIG. 12; It is a flow chart which shows an example of oilway change processing. FIG. 11 is a schematic diagram showing a modified example of the diaphragm;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals are used for the same or corresponding elements, and overlapping descriptions are omitted.

[First embodiment]
FIG. 1 is a schematic diagram showing the configuration of the oil deterioration estimation device of the first embodiment. As shown in FIG. 1 , an oil deterioration estimation device 100 is a device that estimates deterioration of engine oil 2 of an engine (internal combustion engine) 1 .

The oil deterioration estimation device 100 includes an engine 1 and an ECU [Electronic Control Unit] 10 . The engine 1 is, for example, a four-stroke reciprocating engine, although not particularly limited. The engine 1 may be mounted on a vehicle. Deterioration of the engine oil 2 includes a decrease in base number in the oil. As the deterioration of the engine oil 2 progresses, the viscosity of the engine oil 2 increases.

The engine 1 has a pump 4 for pumping the engine oil 2 to the oil passage 3 and a throttle portion 6 provided downstream of the pump 4 and upstream of the lubrication target 5 in the oil passage 3 . The oil passage 3 is a flow passage through which the engine oil 2 flows to the lubrication object 5 . The oil passage 3 includes, for example, a tubular member connecting the pump 4 and the cylinder head 1a. In the oil passage 3, a relief valve (not shown) may be provided immediately after the pump 4 and an oil filter (not shown) downstream of the relief valve between the pump 4 and the lubrication target 5.

The pump 4 sucks the engine oil 2 stored in the oil pan 1b through the oil strainer 3a. The pump 4 pumps the engine oil 2 in the oil passage 3 toward the lubrication target 5 . The lubrication object 5 means a part to be lubricated with the engine oil 2, such as a piston, a crankshaft and a camshaft. The pump 4 can use a known configuration for 4-stroke reciprocating engines.

The throttle portion 6 is configured to generate a pressure loss of the engine oil 2 by flowing the engine oil 2 pressure-fed by the pump 4 . The throttle portion 6 is provided, for example, downstream from the relief valve and upstream from the lubrication target 5 . The throttle portion 6 may be provided downstream from the oil filter and upstream from the lubrication target 5 . The upstream side of the lubrication target 5 means the upstream side of the component positioned most upstream in the flow direction of the engine oil 2 among the lubrication targets 5 .

As an example, the throttle portion 6 of the present embodiment is formed in a venturi shape including a reduced diameter portion, a minimum diameter portion, and an increased diameter portion arranged from upstream to downstream in the flow direction of the engine oil 2 . The reduced-diameter portion is a portion of the throttle portion 6 whose cross-sectional area gradually decreases along the flow direction of the engine oil 2 . The minimum diameter portion is a portion of the constricted portion 6 that has the smallest cross-sectional area. The expanded diameter portion is a portion of the throttle portion 6 in which the cross-sectional area gradually increases along the flow direction of the engine oil 2 . In the throttle portion 6, the pressure of the engine oil 2 decreases as it flows through the reduced diameter portion and the minimum diameter portion, and the pressure of the engine oil 2 increases as it flows through the minimum diameter portion and the enlarged diameter portion. As a result, the magnitude relationship of the pressure of the engine oil 2 is, in descending order, the upstream side of the reduced diameter portion, the downstream side of the increased diameter portion, and the minimum diameter portion.

The engine 1 includes an intake air amount adjusting section 8 and an injector 9 as actuators for adjusting the output of the engine 1 . The intake air amount adjusting section 8 is, for example, an electronically controlled throttle valve. The intake air amount adjustment unit 8 adjusts the output of the engine 1 by adjusting the amount of air supplied into the cylinder. The intake air amount adjustment unit 8 may be, for example, a waste gate valve, a variable nozzle, or the like for adjusting the intake air amount of the turbo. The injector 9 adjusts the output of the engine 1 by adjusting the amount of fuel injected into the cylinder, for example. The operations of the intake air amount adjusting section 8 and the injector 9 are controlled by the ECU 10 .

In the engine 1, an oil pan heater (heater) 7 is provided, for example, in the oil pan 1b. The oil pan heater 7 is a heater provided so as to be able to heat the engine oil 2 stored in the oil pan 1b. The energization of the oil pan heater 7 is controlled by the ECU 10 . The heater may be any heater that can heat the engine oil 2, such as a block heater.

The engine 1 is provided with an engine speed sensor (rotational speed acquisition unit) 21 that acquires the rotational speed of the engine 1 . The engine rotation speed sensor 21 may be a known sensor, and acquires, for example, the rotation speed of the crankshaft as the engine rotation speed. The engine speed sensor 21 transmits a signal regarding the engine speed to the ECU 10 . Note that the engine 1 may be provided with an accelerator opening sensor (not shown). The accelerator opening sensor detects the accelerator opening of the accelerator pedal. The accelerator opening sensor transmits a detection signal of the detected accelerator opening to the ECU 10 .

An upstream pressure sensor 22 is provided upstream of the throttle portion 6 in the oil passage 3 . The upstream pressure sensor 22 detects the upstream pressure of the throttle portion 6 and transmits a signal regarding the detected upstream pressure to the ECU 10 .

The pressure upstream of the throttle 6 means the pressure of the engine oil 2 before the pressure drop by the throttle 6 . The upstream pressure of the throttle portion 6 does not necessarily have to be the pressure of the engine oil 2 measured at a position upstream of the throttle portion 6 in the oil passage 3 . For example, the upstream pressure sensor 22 may be provided at the reduced diameter portion of the throttle portion 6 in a range where the pressure is higher than the detection result of the downstream pressure sensor 23, which will be described later.

A downstream pressure sensor 23 is provided at the minimum diameter portion of the throttle portion 6 . The downstream pressure sensor 23 detects the downstream pressure of the throttle portion 6 and transmits a signal regarding the detected downstream pressure to the ECU 10 .

The downstream pressure of the throttle 6 means the pressure of the engine oil 2 after the pressure drop by the throttle 6 . The downstream pressure of the throttle portion 6 does not necessarily have to be the pressure of the engine oil 2 measured at the position in the oil passage 3 where the pressure drop due to the throttle portion 6 is the largest. For example, the downstream pressure sensor 23 may be provided at the expanded diameter portion of the throttle portion 6 in a range where the pressure is lower than the detection result of the upstream pressure sensor 22 . Note that the downstream pressure sensor 23 may be provided at a position downstream of the throttle portion 6 in the oil passage 3 within a range where the pressure is lower than the detection result of the upstream pressure sensor 22 .

The oil deterioration estimating device 100 includes a differential pressure acquisition section that acquires the differential pressure between the upstream pressure and the downstream pressure of the throttle section 6 . The differential pressure means the pressure difference before and after the pressure drop by the restrictor 6 . In this embodiment, the upstream pressure sensor 22 and the downstream pressure sensor 23 function as differential pressure acquisition units.

In the engine 1, an oil temperature sensor (oil temperature acquisition unit) 24 is provided in the oil pan 1b, for example. The oil temperature sensor 24 acquires the temperature (oil temperature) of the engine oil 2 stored in the oil pan 1b. The oil temperature sensor 24 transmits a signal regarding oil temperature to the ECU 10 . The oil temperature sensor 24 may be provided at a position other than the oil pan 1b as long as it can obtain the oil temperature corresponding to the temperature of the engine oil 2 flowing through the throttle portion 6 .

The ECU 10 is an electronic control unit having a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], a CAN [Controller Area Network] communication circuit, and the like. The ECU 10 implements various functions by, for example, loading programs stored in the ROM into the RAM and executing the programs loaded into the RAM by the CPU. The ECU 10 performs comprehensive control for operating the engine 1 . The ECU 10 may be composed of a plurality of electronic units.

FIG. 2 is a diagram showing the functional configuration of the oil deterioration estimating device of FIG. As shown in FIGS. 1 and 2, the ECU 10 includes an oil pan heater 7, an intake air amount adjuster 8, an injector 9, an engine speed sensor 21, an accelerator opening sensor, an upstream pressure sensor 22, a downstream pressure sensor 23, and the oil temperature sensor 24 are communicably connected.

The ECU 10 includes an engine state quantity acquisition unit (oil temperature acquisition unit, rotation speed acquisition unit) 11, a differential pressure acquisition unit 12, an estimated viscosity calculation unit 13, a deterioration degree estimation unit (estimation unit) 14, and an engine control unit. 15 and a heater control unit 16 .

The engine state quantity acquisition unit 11 acquires engine state quantities based on the detection results of various sensors. The engine state quantity acquisition unit 11 acquires the engine speed and the accelerator opening based on the detection results of the engine speed sensor 21 and the accelerator opening sensor. The engine state quantity acquisition unit 11 acquires the temperature of the engine oil 2 stored in the oil pan 1b based on the detection result of the oil temperature sensor 24 .

The engine state quantity acquisition unit 11 can acquire the required output torque of the engine 1 by a known method based on the engine speed and the accelerator opening. The required output torque may be, for example, a torque value acquired from a pre-stored map or the like.

The differential pressure acquisition unit 12 acquires the differential pressure between the upstream pressure and the downstream pressure of the restrictor 6 . In this embodiment, the differential pressure acquisition unit 12 obtains, for example, the pressure value of the difference between the detection value of the upstream pressure sensor 22 and the detection value of the downstream pressure sensor 23 as the differential pressure between the upstream pressure and the downstream pressure of the throttle unit 6. to get as

FIG. 3 is a diagram for explaining an increase in viscosity of upstream pressure due to deterioration. In FIG. 3 , the horizontal axis is the engine speed, and the vertical axis is the upstream pressure detected at the position of the upstream pressure sensor 22 . It should be noted that FIG. 3 is not necessarily a map used in the ECU 10, but represents the relationship between the engine speed and the upstream pressure obtained by experiments or the like.

In FIG. 3, P1a and P1b are both upstream pressures at the same engine speed N1. P1r corresponds to the set pressure of the relief valve and is the upstream pressure when the set pressure is reached. The engine speed N1 is the engine speed at which the upstream pressure of the new oil and the upstream pressure of the deteriorated oil are less than the set pressure of the relief valve. The engine speed N2 is the engine speed at which the upstream pressure of the new oil and the upstream pressure of the deteriorated oil reach the set pressure of the relief valve.

As shown in FIG. 3, when comparing the new oil and the deteriorated oil at the same engine speed N1, the upstream pressure P1b of the deteriorated oil is higher than the upstream pressure P1a of the new oil due to the viscosity increase due to deterioration. As the engine speed increases, the pressure of the engine oil 2 pumped from the pump 4 increases. At the engine speed N2, the upstream pressure of the new oil and the upstream pressure of the deteriorated oil reach the set pressure of the relief valve, and both become P1r.

FIG. 4 is a diagram for explaining an increase in viscosity of downstream pressure due to deterioration. 4, the horizontal axis is the upstream pressure detected at the position of the upstream pressure sensor 22 (upstream pressure in FIG. 3), and the vertical axis is the downstream pressure detected at the position of the downstream pressure sensor . It should be noted that FIG. 4 is not necessarily a map used in the ECU 10, but represents the relationship between the engine speed and the upstream pressure obtained by experiments or the like.

In FIG. 4, P2a and P2b are downstream pressures at the same engine speed N1. P2a is the downstream pressure corresponding to the upstream pressure P1a on the straight line L1 having a slope when the engine oil 2 is new oil. P2b is the downstream pressure corresponding to the upstream pressure P1b on the straight line L2 having a slope when the engine oil 2 is degraded oil. The slope of the straight line L2 indicating that the engine oil 2 is degraded oil is greater than the slope of the straight line L1 indicating that the engine oil 2 is new oil. This difference in inclination corresponds to the fact that the pressure loss of the engine oil 2 at the throttle portion 6 increases as the viscosity of the engine oil 2 increases due to deterioration.

In FIG. 4, P2ra and P2rb are downstream pressures at the same engine speed N2. P2ra is the downstream pressure corresponding to the upstream pressure P1r on the straight line L1 where the engine oil 2 represents new oil. P2rb is the downstream pressure corresponding to the upstream pressure P1r on the straight line L2 where the engine oil 2 represents deteriorated oil. The differential pressure ΔPr, which is the difference between the downstream pressure P2rb and the downstream pressure P2ra, corresponds to the increase in the pressure loss of the engine oil 2 at the throttle portion 6, which increases as the viscosity of the engine oil 2 increases due to deterioration.

3 and 4, the engine speed and the temperature of the engine oil 2 are constant. Therefore, for example, in experiments, the relationships shown in FIGS. 3 and 4 are obtained for each engine speed, and the relationships shown in FIGS. 3 and 4 are obtained for each temperature of the engine oil 2 .

In the following, for the sake of simplicity of explanation, the engine speed is N2, the oil temperature is oil temperature Tr (see FIG. 5), and both the upstream pressure of new oil and the upstream pressure of deteriorated oil are P1r. A case will be described as an example.

The estimated viscosity calculator 13 estimates an increase in the viscosity of the engine oil 2 based on the differential pressure acquired by the differential pressure acquirer 12 . The estimated viscosity calculation unit 13 calculates the amount of increase in the estimated viscosity of the engine oil 2 based on, for example, the downstream pressure P2ra, which is the downstream pressure of the new oil, the differential pressure ΔPr obtained from the relationship shown in FIG. 4, and the oil temperature. Calculate The estimated viscosity is an estimated value of the viscosity of the engine oil 2 .

FIG. 5 is a diagram for explaining calculation of the amount of increase in estimated viscosity. In FIG. 5 , the horizontal axis is the oil temperature, and the vertical axis is the estimated viscosity of the engine oil 2 . As shown in FIG. 5, the solid curve indicates the relationship of the estimated viscosity of the new oil to the oil temperature at a constant engine speed. Also, the dashed-dotted curve indicates the relationship between the oil temperature and the estimated viscosity of the deteriorated oil at a constant engine speed. In FIG. 5, Va is the estimated viscosity at the oil temperature Tr when the engine oil 2 is new oil. Vb is the estimated viscosity at the oil temperature Tr when the engine oil 2 is degraded oil.

The estimated viscosity indicated by the solid line can be obtained, for example, from an experiment using fresh oil at a constant engine speed. The estimated viscosity indicated by the solid line is pre-stored in the ECU 10 for each predetermined engine speed as a map using, for example, the downstream pressure of new oil and the oil temperature as arguments. The estimated viscosity calculator 13 calculates the estimated viscosity Va of the new oil, for example, based on the downstream pressure P2ra, which is the downstream pressure of the new oil, and the oil temperature.

The estimated viscosity indicated by the dashed-dotted line can be obtained, for example, from an experiment using degraded oil at a constant engine speed. The difference between the one-dot chain line and the solid line at the same oil temperature (that is, the increase in the estimated viscosity) can be obtained, for example, as a map whose arguments are the differential pressure of the downstream pressure between the deteriorated oil and the new oil at the same upstream pressure and the oil temperature. It is stored in the ECU 10 for each predetermined engine speed. The estimated viscosity calculation unit 13 calculates the amount of increase in the estimated viscosity based on, for example, the differential pressure ΔPr (the differential pressure between the deteriorated oil and the new oil at the same upstream pressure) obtained from the relationship shown in FIG. 4 and the oil temperature. ΔV is calculated.

The estimated viscosity calculation unit 13 may calculate the estimated viscosity Vb of the deteriorated oil by adding the estimated viscosity increase amount ΔV to the estimated viscosity Va of the new oil.

The deterioration degree estimator 14 estimates the degree of deterioration corresponding to the increase in the viscosity of the engine oil 2 due to deterioration, based on the differential pressure between the upstream pressure and the downstream pressure of the throttle portion 6 . For example, the deterioration degree estimation unit 14 calculates the estimated viscosity Vb of the deteriorated oil calculated by the estimated viscosity calculation unit 13 based on the differential pressure ΔPr obtained from the relationship shown in FIG. 4 and the deterioration degree threshold value Dth shown in FIG. is used to estimate the degree of deterioration.

FIG. 6 is a diagram for explaining the first deterioration determination. The first deterioration determination is a deterioration determination of the engine oil 2 by the oil deterioration estimation device 100 of the first embodiment, and is performed using the estimated viscosity. The horizontal axis of FIG. 6 is the estimated viscosity, and the vertical axis is the degree of deterioration. As indicated by the dashed-dotted line in FIG. 6, the degree of deterioration is defined so that the degree of deterioration increases as the estimated viscosity increases, with the degree of deterioration assumed to be 0 when the estimated viscosity Va is new oil. In the case of degraded oil with an estimated viscosity of Vb, the degree of deterioration is Db. Here, the deterioration degree threshold Dth is a deterioration degree threshold for determining that the engine oil 2 has reached the end of its life.

For example, the deterioration degree estimating unit 14 determines that the engine oil 2 is deteriorated when the viscosity increase (estimated viscosity increase amount ΔV) estimated by the estimated viscosity calculating unit 13 is equal to or greater than a predetermined deterioration viscosity threshold value (second threshold value). It is determined that In the example of FIG. 6, the deteriorated viscosity threshold corresponds to a value obtained by subtracting the estimated viscosity Va from the estimated viscosity Vz.

The engine control unit 15 controls the engine 1 by controlling the intake air amount adjusting unit 8 and the injector 9 so as to output the required output torque. In this embodiment, the engine control unit 15 restricts the operation of the engine 1 when the deterioration degree estimating unit 14 determines that the engine oil 2 has deteriorated. The operation restriction of the engine 1 means operation in which the output of the engine 1 is restricted in accordance with deterioration of the protection performance of the engine oil 2 .

For example, the engine control unit 15 controls the engine 1 so as to reduce the maximum rotation speed (rev limit rotation speed) of the engine 1 compared to when the deterioration degree estimation unit 14 does not determine that the engine oil 2 has deteriorated. do. The engine control unit 15 controls the engine 1 so as to output an output torque during protection smaller than the required output torque, for example, compared to when the deterioration degree estimating unit 14 does not determine that the engine oil 2 has deteriorated. You may

The heater control unit 16 heats the engine oil 2 when the increase in viscosity (increase in estimated viscosity ΔV) estimated by the estimated viscosity calculation unit 13 is equal to or greater than a predetermined warm-up viscosity threshold (third threshold). The oil pan heater 7 is controlled as follows. The warm-up viscosity threshold is a threshold for the amount of increase in estimated viscosity for determining whether or not to heat the engine oil 2 . The warm-up viscosity threshold is smaller than the deteriorated viscosity threshold (second threshold).

FIG. 7 is a diagram for explaining heater heating determination. FIG. 7 shows a dashed curve below the one-dot chain line in FIG. 5 representing degraded oil. The dashed curve in FIG. 7 corresponds to the warm-up viscosity threshold. In the example of FIG. 7, the warm-up viscosity threshold corresponds to a value obtained by subtracting the estimated viscosity Va from the estimated viscosity Vh. If the estimated viscosity is Vh or more and less than Vz, the engine oil 2 has not reached the end of its service life, but the viscosity is increasing at low temperatures rather than deterioration, such as when starting in a low temperature environment. Therefore, by heating the engine oil 2 with the oil pan heater 7, the viscosity of the engine oil 2 can be reduced and the startability can be improved.

Next, an example of processing by the ECU 10 will be described. FIG. 8 is a flow chart showing an example of the first deterioration determination process. The processing shown in FIG. 8 is repeatedly executed, for example, at predetermined calculation cycles while the engine 1 is running.

As shown in FIG. 8, the ECU 10 acquires the differential pressure using the differential pressure acquisition unit 12 in S01. The differential pressure acquisition unit 12 acquires, for example, the pressure value of the difference between the detection value of the upstream pressure sensor 22 and the detection value of the downstream pressure sensor 23 as the differential pressure between the upstream pressure and the downstream pressure of the restrictor 6 .

In S<b>02 , the ECU 10 causes the estimated viscosity calculation unit 13 to calculate an increase amount of the estimated viscosity. The estimated viscosity calculator 13, for example, as shown in FIG. 5, calculates the estimated viscosity Va of the new oil based on the downstream pressure P2ra, which is the downstream pressure of the new oil, and the oil temperature. The estimated viscosity calculation unit 13 calculates the amount of increase in the estimated viscosity based on, for example, the differential pressure ΔPr (the differential pressure between the deteriorated oil and the new oil at the same upstream pressure) obtained from the relationship shown in FIG. 4 and the oil temperature. ΔV is calculated. The estimated viscosity calculator 13 may calculate the estimated viscosity Vb of the deteriorated oil by adding the estimated viscosity increase ΔV to the estimated viscosity Va of the new oil.

In S03, the degree-of-degradation estimating unit 14 of the ECU 10 determines whether or not the increase amount ΔV of the estimated viscosity of the degraded oil is greater than or equal to the threshold value for degraded viscosity. When it is determined that the increase amount ΔV of the estimated viscosity of the deteriorated oil is not equal to or greater than the threshold value of deteriorated viscosity (S03: NO), the ECU 10 determines in S04 that the engine oil 2 is not deteriorated by the deterioration degree estimator 14. . After that, the ECU 10 terminates the processing of FIG.

On the other hand, when the deterioration degree estimating unit 14 determines that the increase amount ΔV of the estimated viscosity of the deteriorated oil is equal to or greater than the deterioration viscosity threshold value (S03: YES), the ECU 10 causes the deterioration degree estimating unit 14 to is determined to have deteriorated. The ECU 10 restricts the operation of the engine 1 by the engine control unit 15 in S06. For example, the engine control unit 15 controls the engine 1 so as to reduce the maximum rotation speed (rev limit rotation speed) of the engine 1 compared to when the deterioration degree estimation unit 14 does not determine that the engine oil 2 has deteriorated. do. After that, the ECU 10 terminates the processing of FIG.

FIG. 9 is a flowchart showing an example of heater heating processing. The processing shown in FIG. 9 is, for example, repeatedly executed in parallel with the processing in FIG. 8 at predetermined calculation cycles.

In S11, the ECU 10 uses the heater control unit 16 to determine whether or not the increase amount ΔV of the estimated viscosity of the deteriorated oil is equal to or greater than the warm-up viscosity threshold. When the degree-of-deterioration estimation unit 14 determines that the increase amount ΔV of the estimated viscosity of the deteriorated oil is equal to or greater than the warm-up viscosity threshold (S11: YES), the ECU 10 causes the heater control unit 16 to operate the oil pan heater 7 in S12. It is turned ON to heat the engine oil 2. After that, the ECU 10 terminates the processing of FIG.

On the other hand, when it is determined that the increase amount ΔV of the estimated viscosity of the deteriorated oil is not equal to or greater than the warm-up viscosity threshold (S11: NO), the ECU 10 turns off the oil pan heater 7 by the heater control unit 16 in S13. Do not heat oil 2. After that, the ECU 10 terminates the processing of FIG.

[Action and effect of the first embodiment]
As described above, according to the oil deterioration estimating device 100 , the throttle section 6 is provided downstream of the pump 4 for pumping the engine oil 2 in the oil passage 3 and upstream of the lubrication target 5 . At this throttle portion 6 , pressure loss occurs in the engine oil 2 flowing through the oil passage 3 . The degree of this pressure loss increases as the viscosity of the engine oil 2 increases. That is, the pressure loss of the engine oil 2 at the throttle portion 6 increases as the viscosity of the engine oil 2 increases due to deterioration. Therefore, the degree of pressure loss of the engine oil 2 can be estimated by the deterioration degree estimating section 14 based on the differential pressure between the upstream pressure and the downstream pressure of the throttle section 6 . Therefore, according to the oil deterioration estimating device 100, the deterioration of the engine oil 2 of the engine 1 can be estimated by utilizing the viscosity increase of the engine oil 2 due to deterioration with a simple configuration.

The oil deterioration estimating device 100 includes an estimated viscosity calculator 13 for estimating the increase ΔV of the estimated viscosity based on the differential pressure ΔPr obtained from the relationship shown in FIG. 4 . The deterioration degree estimator 14 determines that the engine oil 2 has deteriorated when the estimated viscosity increase amount ΔV is equal to or greater than a predetermined deterioration viscosity threshold value (second threshold value). As a result, the degree of increase in the viscosity of the engine oil 2 can be estimated from the degree of increase in the differential pressure using the relationship between the degree of increase in the viscosity of the engine oil 2 and the degree of increase in the differential pressure (relationship in FIG. 5) obtained in advance. The degree of deterioration of the engine oil 2 can be estimated based on the fact that the degree of viscosity increase exceeds a certain level.

The oil deterioration estimating device 100 is configured so that the increase in viscosity estimated by the oil pan heater 7 that can heat the engine oil 2 and the degree of deterioration estimating section 14 is equal to or greater than a predetermined warm-up viscosity threshold (third threshold). and a heater control unit 16 that controls the oil pan heater 7 so as to heat the engine oil 2 in the case where the engine oil 2 is heated. The warm viscosity threshold is less than the deteriorated viscosity threshold. Therefore, for example, when the viscosity of the engine oil 2 increases at a low temperature instead of deterioration, such as when starting in a low temperature environment, by heating the engine oil 2 with the oil pan heater 7, the viscosity of the engine oil 2 is reduced and the startability is improved. can be improved.

The oil deterioration estimation device 100 further includes an engine control unit 15 that limits the operation of the engine 1 when the deterioration degree estimation unit 14 determines that the engine oil 2 has deteriorated. When it is determined that the engine oil 2 has deteriorated, there is a possibility that the engine oil 2 has deteriorated protective performance due to deterioration. Therefore, by restricting the operation of the engine 1, the engine 1 can be protected.

[Modification of First Embodiment]
The oil deterioration estimation device 100 of the first embodiment includes the estimated viscosity calculation unit 13 that estimates the increase amount ΔV of the estimated viscosity based on the differential pressure ΔPr obtained from the relationship of FIG. 13 may be omitted. In this case, the deterioration degree estimation unit 14 may directly estimate the deterioration degree from the differential pressure ΔPr obtained by the differential pressure acquisition unit 12 from the relationship of FIG.

Here, in FIG. 5 described above, the amount of increase ΔV in the estimated viscosity of the engine oil 2 was calculated, and the amount of increase ΔV corresponds to the differential pressure ΔPr of the downstream pressure increased due to deterioration. Further, in FIG. 5, the estimated viscosity and the amount of increase ΔV have a relationship for each oil temperature and engine speed. Therefore, the differential pressure .DELTA.Pr of the downstream pressure, which has increased due to deterioration, can also be treated as representing the degree of deterioration based on new oil for each oil temperature and engine speed. That is, the relationship between the degree of increase in the differential pressure and the degree of deterioration of the engine oil 2 can be arranged for each oil temperature and engine speed. Therefore, the deterioration degree estimating unit 14 determines that the differential pressure ΔPr is a predetermined deterioration differential pressure threshold (the second 1 threshold) or more, it may be determined that the engine oil 2 has deteriorated.

FIG. 10 is a diagram for explaining the second deterioration determination. The second deterioration determination is a deterioration determination of the engine oil 2 by the oil deterioration estimation device 100 according to the modified example of the first embodiment, and is performed directly from the differential pressure ΔPr without using the estimated viscosity. The horizontal axis of FIG. 10 is the differential pressure (the differential pressure between the new oil and the deteriorated oil at the same upstream pressure), and the vertical axis is the degree of deterioration. As shown by the dashed line in FIG. 10, since the differential pressure between the downstream pressures of new oil at the same upstream pressure is 0, the degree of deterioration in the case of new oil is assumed to be 0, and the degree of deterioration increases as the differential pressure increases. The degree of deterioration is defined to increase. In the case of degraded oil with a differential pressure ΔPr, the degree of degradation is Db. Here, the deterioration level threshold value Dth is a deterioration level threshold value for determining that the engine oil 2 has reached the end of its service life, as in FIG. 6 . In the example of FIG. 10, the deterioration differential pressure threshold corresponds to the value of the differential pressure ΔPz, which is the differential pressure reaching the deterioration degree threshold Dth.

FIG. 11 is a flowchart illustrating an example of the second deterioration determination process. The processing shown in FIG. 11 is repeatedly executed, for example, at predetermined calculation cycles while the engine 1 is running.

As shown in FIG. 11 , the ECU 10 acquires the differential pressure using the differential pressure acquiring section 12 in S21. The differential pressure acquisition unit 12 acquires the differential pressure in the same manner as S01 in FIG. 8, for example.

In S22, the deterioration degree estimating unit 14 of the ECU 10 determines whether or not the differential pressure ΔPr is equal to or greater than the deterioration differential pressure threshold. When it is determined that the differential pressure ΔPr is not equal to or greater than the degradation differential pressure threshold (S22: NO), the ECU 10 determines in S23 that the engine oil 2 is not degraded by the degradation degree estimator 14 . After that, the ECU 10 terminates the processing of FIG.

On the other hand, when the deterioration degree estimation unit 14 determines that the differential pressure ΔPr is equal to or greater than the deterioration differential pressure threshold value (S22: YES), the ECU 10 determines in S24 that the deterioration degree estimation unit 14 has deteriorated the engine oil 2. do. In S25, the ECU 10 restricts the operation of the engine 1 by the engine control unit 15 in the same manner as in S06 of FIG. After that, the ECU 10 terminates the processing of FIG.

As described above, the oil deterioration estimation device 100 according to the modification of the first embodiment includes the engine state quantity acquisition unit (oil temperature acquisition unit) 11 that acquires the temperature of the engine oil 2 (oil temperature), and the rotation speed of the engine 1 and an engine state quantity acquisition unit (rotational speed acquisition unit) 11 to be acquired. The deterioration degree estimator 14 determines that the engine oil 2 has deteriorated based on the differential pressure ΔPr, the oil temperature, and the engine speed when the differential pressure ΔPr is equal to or greater than a predetermined degradation differential pressure threshold. As a result, the degree of deterioration of the engine oil 2 can be estimated from the degree of increase in the differential pressure by utilizing the fact that the relationship between the degree of increase in the differential pressure and the degree of deterioration of the engine oil 2 can be arranged for each temperature and rotation speed. .

[Second embodiment]
An oil deterioration estimation device 100A of the second embodiment will be described with reference to FIGS. 12 to 14. FIG. FIG. 12 is a schematic diagram showing the configuration of the oil deterioration estimation device of the second embodiment. FIG. 13 is a diagram showing the functional configuration of the oil deterioration estimating device of FIG. 12; As shown in FIGS. 12 and 13, the oil deterioration estimation device 100A differs from the oil deterioration estimation device 100 in that the upstream pressure sensor 22 and the downstream pressure sensor 23 are replaced with a differential pressure sensor 25 in the engine 1A. 3, the throttle section 6 is replaced with a variable throttle section 6A, and the oil pan heater 7 is omitted. The ECU 10A is different from the ECU 10 in that the oil pan heater 7 is omitted and the heater control section 16 is omitted, and the ECU 10A is provided with an oil passage switching section 17 that controls the variable throttle section 6A. It is different in point.

The differential pressure sensor 25 is a sensor that detects the differential pressure between the upstream pressure of the throttle portion 6 and the downstream pressure of the throttle portion 6 . In the example of FIG. 12, the differential pressure sensor 25 acquires the pressure upstream of the throttle portion 6 in the oil passage 3 as the upstream pressure of the throttle portion 6, and detects the pressure at the enlarged diameter portion of the throttle portion 6 in the oil passage 3. The differential pressure is detected by obtaining the downstream pressure of the throttle section 6 and calculating the difference between these pressures. That is, the differential pressure between the upstream pressure of the throttle section 6 and the downstream pressure of the throttle section 6 is not limited to the example of being detected by two sensors such as the upstream pressure sensor 22 and the downstream pressure sensor 23 , and is detected by the differential pressure sensor 25 . may be detected by a single sensor. The differential pressure sensor 25 transmits a signal regarding the differential pressure between the upstream pressure of the throttle portion 6 and the downstream pressure of the throttle portion 6 as a detection result to the ECU 10A.

The variable throttle portion 6A has a bypass oil passage 3A in parallel with the oil passage 3 and the throttle portion 6 of the first embodiment. The bypass oil passage 3</b>A circulates the engine oil 2 from the pump 4 to the lubrication object 5 , but differs from the oil passage 3 in that it does not have the throttle portion 6 .

The variable throttle portion 6A is configured to allow the engine oil 2 to flow through either the oil passage 3 or the bypass oil passage 3A by means of a switching valve 6Aa. The switching valve 6Aa is controlled by an oil passage switching section 17 of the ECU 10A.

The oil passage switching unit 17 switches the switching valve 6Aa, for example, depending on whether the deterioration determination execution condition is satisfied. The deterioration determination execution condition is a condition as to whether or not the deterioration determination of the engine oil 2 is to be performed by the deterioration degree estimating section 14 .

The oil passage switching unit 17 may determine that the deterioration determination execution condition is met, for example, when the cumulative history of the engine speed is equal to or greater than a certain threshold value. For example, the oil passage switching unit 17 may determine that the deterioration determination execution condition is met when the cumulative traveled distance of the vehicle equipped with the engine 1A is greater than or equal to a certain threshold value. The oil passage switching unit 17 may determine that the deterioration determination execution condition is established, for example, when the accumulated operating time of the engine 1A is equal to or greater than a certain threshold value. The oil passage switching unit 17 controls the switching valve 6</b>Aa so that the engine oil 2 can flow through the oil passage 3 when it is determined that the deterioration determination execution condition is satisfied. The deterioration degree estimator 14 performs deterioration determination of the engine oil 2 in the same manner as in the first embodiment (including the modification of the first embodiment).

On the other hand, when determining that the deterioration determination execution condition is not satisfied, the oil passage switching unit 17 controls the switching valve 6Aa so that the engine oil 2 can flow through the bypass oil passage 3A.
In this case, pressure loss of the engine oil 2 can be suppressed by preventing the engine oil 2 from flowing through the throttle portion 6 when the deterioration determination is not performed.

FIG. 14 is a flowchart showing an example of oil passage switching processing. The process shown in FIG. 14 is repeatedly executed, for example, at predetermined calculation cycles while the engine 1A is running.

As shown in FIG. 14, in S31, the ECU 10 uses the oil passage switching unit 17 to determine the deterioration determination execution condition. The oil passage switching unit 17 may determine that the deterioration determination execution condition is met, for example, when the cumulative history of the engine speed is equal to or greater than a certain threshold value.

In S32, the ECU 10 uses the oil passage switching unit 17 to determine whether or not the deterioration determination execution condition is satisfied. When it is determined that the deterioration determination execution condition is satisfied (S32: YES), the ECU 10 controls the variable throttle section 6A so that the oil passage switching section 17 uses the throttle flow path in S33. The oil passage switching unit 17 controls the switching valve 6Aa so that the engine oil 2 can flow through the oil passage 3, for example. After that, the ECU 10 terminates the processing of FIG.

On the other hand, when it is determined that the deterioration determination execution condition is not satisfied (S32: NO), the ECU 10 controls the variable throttle section 6A so that the oil passage switching section 17 does not use the throttle flow path in S34. . The oil passage switching unit 17, for example, controls the switching valve 6Aa so that the engine oil 2 can flow through the bypass oil passage 3A. After that, the ECU 10 terminates the processing of FIG.

As described above, according to the oil deterioration estimation device 100A of the second embodiment, when the deterioration determination is not performed, the engine oil 2 is not allowed to flow through the throttle portion 6, so that the pressure loss of the engine oil 2 caused by passing through the throttle portion 6 is reduced. can suppress the occurrence of Therefore, the pumping load of the pump 4 when deterioration determination is not performed can be suppressed compared to when deterioration determination is performed, which is advantageous in terms of fuel consumption of the engine 1A, for example.

[Modification]
Although the embodiments according to the present invention have been described above, the present invention is not limited to the above-described embodiments.

In the above-described embodiment, the throttle portion 6 is formed in a venturi shape including a reduced diameter portion, a minimum diameter portion, and an enlarged diameter portion arranged from the upstream side to the downstream side in the flow direction of the engine oil 2. Not limited. For example, as shown in FIG. 15, it may be an orifice 6B. To construct the venturi shape, for example, the three parts of the reduced diameter portion, the minimum diameter portion and the enlarged diameter portion are welded together or by press drawing. It can be constructed by welding perforated plates. Therefore, it is possible to reduce the number of parts or the number of processing steps.

In the above-described embodiment, the throttle portion 6 is provided downstream of the relief valve (not shown) immediately after the pump 4 and upstream of the lubrication target 5, but the present invention is not limited to this. For example, it may be provided immediately after the pump 4 and upstream of the relief valve.

In the above embodiment, the engine control unit 15 is provided to limit the operation of the engines 1 and 1A when the deterioration degree estimating unit 14 determines that the engine oil 2 has deteriorated. Not required.

In the above embodiment, for the sake of simplification of explanation, the condition of the engine speed is the engine speed N2, but the present invention is not limited to this. For example, when the upstream pressure is different between the new oil and the deteriorated oil, as in the case where the engine speed is the engine speed N1, the pressure of the engine oil 2 of the reference new oil is different even on the upstream side. Become. Therefore, the differential pressure acquisition unit 12 may directly subtract the downstream pressure P2a from the downstream pressure P2b in FIG. 4 when calculating the differential pressure between the new oil and the deteriorated oil. Correction may be performed so as to reduce the difference in the pressure of the engine oil 2 of the reference new oil using the difference in upstream pressure from the oil (difference between P1b and P1a).

DESCRIPTION OF SYMBOLS 1, 1A... Engine (internal combustion engine), 2... Engine oil, 3... Oil passage, 4... Pump, 5... Lubrication object, 6... Throttle part, 7... Oil pan heater (heater), 11... Engine state quantity acquisition part (Oil temperature acquisition unit, rotation speed acquisition unit) 12 Differential pressure acquisition unit 13 Estimated viscosity calculation unit 14 Degradation degree estimation unit (estimation unit) 15 Engine control unit 16 Heater control unit 21 ...engine speed sensor (rotational speed acquisition unit), 24...oil temperature sensor (oil temperature acquisition unit), 100, 100A...oil deterioration estimator, P1a, P1b, P1r...upstream pressure, P2a, P2b, P2ra, P2rb... Downstream pressure, ΔPr, ΔPz... differential pressure, Va, Vb, Vz... estimated viscosity, ΔV... increase in estimated viscosity.

Claims (5)

An oil deterioration estimation device for estimating deterioration of engine oil in an internal combustion engine,
a pump that pressure-feeds the engine oil to the oil passage;
a throttle portion provided in the oil passage downstream of the pump and upstream of the object to be lubricated;
a differential pressure acquisition unit that acquires the differential pressure between the upstream pressure and the downstream pressure of the throttle;
an estimating unit for estimating a degree of deterioration corresponding to an increase in viscosity of the engine oil due to deterioration, based on the differential pressure. an oil temperature acquisition unit that acquires the temperature of the engine oil;
A rotation speed acquisition unit that acquires the rotation speed of the internal combustion engine,
2. The estimating unit according to claim 1, wherein the estimating unit determines that the engine oil has deteriorated based on the differential pressure, the temperature, and the rotational speed when the differential pressure is equal to or greater than a predetermined first threshold. Oil degradation estimator. Further comprising an estimated viscosity calculation unit for estimating the increase in viscosity based on the differential pressure,
The oil deterioration estimation device according to claim 1, wherein the estimation unit determines that the engine oil has deteriorated when the increase in viscosity estimated by the estimated viscosity calculation unit is equal to or greater than a predetermined second threshold. a heater capable of heating the engine oil;
a heater control unit that controls the heater to heat the engine oil when the increase in the viscosity estimated by the estimated viscosity calculation unit is equal to or greater than a predetermined third threshold that is smaller than the second threshold; 4. The oil deterioration estimator of claim 3, further comprising: The oil deterioration estimation device according to any one of claims 2 to 4, further comprising an engine control unit that restricts operation of the engine when the estimation unit determines that the engine oil has deteriorated.

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