JP2010084709A - Oil degradation determining device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of accurately determining the degradation of lubricating oil in an internal combustion engine. <P>SOLUTION: This oil degradation determining device includes a friction measuring means for measuring the friction of the internal combustion engine, and a determination means for measuring the friction of the internal combustion engine with the friction measuring means and determining the degradation of the lubricating oil in the internal combustion engine based on the relation of the measured friction values for each of at least two different kinds of operating conditions indicating different friction characteristics in a state where the lubricating oil of the internal combustion engine is degraded. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an oil deterioration determination device for an internal combustion engine.

A technique for determining the deterioration of lubricating oil in an internal combustion engine based on the relationship between friction and the degree of deterioration of fuel consumption is known (see, for example, Patent Document 1).
JP 2007-211685 A

  In recent years, internal combustion engines using low-viscosity lubricating oil have been developed to reduce fuel consumption. By using low-viscosity oil, the oil film thickness is reduced and friction is reduced, so that fuel efficiency can be improved. However, in an internal combustion engine that uses low-viscosity oil, when the viscosity of the oil further decreases due to heat deterioration due to frictional heat or high-load high-speed operation, or deterioration due to dilution by blow-by gas, unburned fuel, condensed water, soot, etc. The oil film is likely to run out, and in that case, friction may increase significantly.

  Therefore, particularly in an internal combustion engine using low-viscosity oil, it is required to accurately determine the deterioration of the oil. However, in the above prior art, it is difficult to accurately determine the deterioration of the oil when the change in the friction is caused by the abnormality of the parts such as the piston ring and the cylinder liner.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a technique that can more accurately determine the deterioration of lubricating oil in an internal combustion engine.

In order to achieve the above object, an oil deterioration determination device for an internal combustion engine of the present invention includes:
Friction measuring means for measuring the friction of the internal combustion engine;
Based on the relationship of the measured friction, the friction measuring means measures the friction of the internal combustion engine under each of at least two different operating conditions that exhibit different friction characteristics when the lubricating oil of the internal combustion engine is deteriorated. Determining means for determining deterioration of the lubricating oil of the internal combustion engine;
It is characterized by providing.

  The present invention focuses on the fact that the relationship between the deterioration state of the lubricating oil and the friction of the internal combustion engine differs depending on the operating conditions. For example, even when the viscosity of the oil has decreased to such an extent that the friction can increase beyond an acceptable level due to deterioration of the oil, the viscosity of the oil is higher in a low temperature environment than in a high temperature environment. Therefore, in a low temperature environment, the deterioration of oil may not cause an increase in friction. The “predetermined allowable level” of friction is a reference value of friction that is determined in advance so as to satisfy requirements such as fuel efficiency.

As described above, even if the oil deterioration state is the same, different friction characteristics may be exhibited depending on the operating conditions. Therefore, at least two different operating conditions that show different friction characteristics in the same oil deterioration state are set in advance. If the friction is measured under each of the different operating conditions and the deterioration of the oil is judged based on the relationship of the measured friction, the increase in the friction due to the deterioration of the oil and the deterioration of the oil can be prevented. It is possible to accurately determine the deterioration of the oil by determining the resulting increase in friction.

  For example, the friction increases even when the internal combustion engine parts such as piston rings and cylinder liners are damaged. Therefore, it may not be possible to determine whether the increase in friction is due to the deterioration of the oil or the abnormality of the internal combustion engine only based on the increase in friction under a certain operating condition.

  In this regard, according to the present invention, friction under different operating conditions showing different friction characteristics is measured even if the deterioration state of the oil is the same. If there is an abnormality in the internal combustion engine, the friction is considered to exceed the permissible level when measured under any operating condition, but there is no abnormality in the internal combustion engine and the oil has deteriorated. It is considered that the friction measured under one operating condition and the friction measured under another operating condition tend to have different magnitude relations with the allowable level.

  As described above, according to the present invention, it is possible to accurately discriminate between oil deterioration and internal combustion engine abnormality.

  In the present invention, “at least two different operating conditions showing different friction characteristics when the lubricating oil of the internal combustion engine is deteriorated” can be exemplified by a predetermined light load operating state and a predetermined high load operating state. The “predetermined light load operation state” is an operation state in which friction exceeding the allowable level does not occur in the internal combustion engine even when the oil has deteriorated beyond a predetermined degree of deterioration that should be changed. is there. The “predetermined high-load operation state” is an operation state in which friction exceeding an allowable level is generated in the internal combustion engine in a state in which the oil has deteriorated beyond a predetermined degree of deterioration that should be changed.

And the judging means is
Light load friction measured by the friction measuring means in a predetermined light load operating state of the internal combustion engine;
High load friction measured by the friction measuring means in a predetermined high load operating state of the internal combustion engine;
Based on the relationship, it is possible to determine the deterioration of the lubricating oil of the internal combustion engine.

  In the above configuration, attention is focused on the fact that the viscosity of the oil depends on the load condition of the internal combustion engine. That is, in the light load operation state, the temperature of the internal combustion engine is low and the viscosity of the oil is relatively high. On the other hand, in a high load operation state, the temperature of the internal combustion engine is high, and the viscosity of the oil is relatively low. For this reason, even if the oil viscosity is so low as to cause the internal combustion engine to generate friction exceeding the allowable level due to deterioration, the oil viscosity increases under low temperature conditions in the light load operation state. In addition, the friction exceeding the allowable level may not be measured. However, even in such a case, in a high-load operation state, an influence due to a decrease in oil viscosity due to deterioration appears significantly, and there is a high possibility that friction exceeding an allowable level is measured.

  On the other hand, if a failure has occurred in parts such as the piston ring and the cylinder liner, it is considered that the friction exceeding the allowable level is measured regardless of the operating state of the internal combustion engine.

In this way, by measuring the friction under at least two different load conditions that cause a significant difference in the viscosity of the oil, and determining the deterioration of the oil based on the measurement result, it is distinguished from the abnormality of the internal combustion engine. In addition, it is possible to determine the deterioration of the oil more accurately.

  In addition, depending on the conventional technology that determines oil deterioration based only on the measured value of friction in light load operation, the viscosity of the oil may actually be deteriorated under low temperature conditions in light load operation. When the value is high, there is a possibility of erroneous determination that there is no oil deterioration.

  In this regard, according to the present invention, not only the friction in the light load operation state but also the friction in the high load operation state is measured, and even if the friction in the light load operation state is below the allowable level, the friction in the high load operation state Is greater than the permissible level, it can be determined that the oil has deteriorated, and thus erroneous determination as described above can be suppressed.

  In addition, depending on the conventional technology that determines oil deterioration based only on the measured value of friction in a light load operation state, even if the oil is not actually deteriorated, if the internal combustion engine parts are damaged, the friction is reduced. Therefore, there is a possibility of erroneous determination that there is oil deterioration based on the increase in friction. In this case, even if the oil is replaced based on the erroneous determination, the increase in the friction is not eliminated, and accordingly, the abnormality determination of the internal combustion engine is performed, so that unnecessary oil replacement is performed as a result. become.

  In this regard, according to the present invention, not only the friction in the light load operation state but also the friction in the high load operation state is measured, and both the friction in the light load operation state and the friction in the high load operation state exceed the allowable level. In this case, since it can be determined that the increase in friction is not caused by oil deterioration but by abnormality of the internal combustion engine, it is possible to suppress the erroneous determination as described above, and the oil deterioration. It is possible to accurately determine the situation where there is no abnormality and the internal combustion engine is abnormal. Therefore, it is possible to suppress useless oil exchange and to detect an abnormality of the internal combustion engine more quickly.

  The present invention measures friction in each of at least two different operating states that exhibit different friction characteristics in the same oil deterioration state, and determines oil deterioration and internal combustion engine abnormality based on the measurement results. The friction measurement conditions do not have to be two types, and if the friction characteristics are different, it is not necessary that the measurement conditions differ from the load conditions of the internal combustion engine.

  According to the present invention, it is possible to more accurately determine the deterioration of the lubricating oil of the internal combustion engine.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the present embodiment are not intended to limit the technical scope of the invention only to those unless otherwise specified.

  FIG. 1 is a conceptual diagram schematically showing a schematic configuration of an engine to which the present invention is applied and its intake system and exhaust system.

The engine 1 is a diesel engine having four cylinders 4. Each cylinder 4 is provided with a fuel injection valve 10 for directly injecting fuel into the cylinder. Each cylinder 4 communicates with an intake manifold 17 via an intake port (not shown). The intake manifold 17 is connected to the intake passage 2. The intake passage 2 is provided with a throttle valve 9, an intercooler 6 on the upstream side, a compressor 11 of a turbocharger 13 on the upstream side, and an air flow meter 7 on the upstream side. On the other hand, each cylinder 4 communicates with the exhaust manifold 18 via an exhaust port (not shown). The exhaust manifold 18 is connected to the exhaust passage 3. The exhaust passage 3 is provided with a turbine 12 of a turbocharger 13 and an exhaust purification device 8 on the downstream side thereof. The turbine 12 is provided with a variable nozzle vane 5.

  The engine 1 is provided with an acceleration sensor 14 and a rotation variometer 15. Each cylinder 4 is provided with a cylinder pressure sensor 24 for measuring the cylinder pressure. Further, an accelerator opening sensor 19 for measuring the opening of the accelerator pedal 22, a vehicle speed sensor 20 for measuring the vehicle speed of the vehicle on which the engine 1 is mounted, and an inclination angle sensor 21 for measuring the inclination of the vehicle are provided.

  The engine 1 includes an ECU 16 that is a computer unit that controls the operating state of the engine 1. The ECU 16 includes a CPU that executes a control program, a ROM that stores the control program, a RAM that temporarily stores measurement data and calculation results, and the like. Various sensors are connected to the ECU 16 in addition to the air flow meter 7, the rotation variometer 15, the in-cylinder pressure sensor 24, the accelerator opening sensor 19, the vehicle speed sensor 20, and the inclination angle sensor 21, and the measured values by these sensors are ECU 16. Is input. In addition to the fuel injection valve 10, the throttle valve 9, and the variable nozzle vane 5 described above, various devices are connected to the ECU 16, and the operations of these devices are controlled by control signals from the ECU 16.

  FIG. 2 is a diagram showing the relationship between the state of the lubricating oil of the engine 1 and the friction. In FIG. 2, the horizontal axis represents the oil state such as the viscosity of the oil, the rotational speed of the engine 1, and the oil film thickness. The vertical axis represents friction (friction coefficient). As shown in FIG. 2, the friction is significantly increased in the region where the oil film is too thin (boundary lubrication region), but in the region where the oil film is thick to some extent (fluid lubrication region), the friction increases as the oil film thickness increases. Therefore, fuel efficiency can be improved by using low-viscosity oil in which the oil film thickness is in the region with the smallest friction (mixed lubrication region).

  Therefore, the engine 1 of this embodiment uses low-viscosity oil as lubricating oil. By the way, as shown in FIG. 2, when low viscosity oil whose oil film thickness is included in the mixed lubrication region is used, thermal deterioration due to frictional heat or high load high rotation operation, blowby gas, unburned fuel, condensation When the viscosity of the oil further decreases due to deterioration due to dilution with water, soot, etc., it easily enters the boundary lubrication region. In the boundary lubrication region, the oil film is likely to run out and the friction is large, which causes a reduction in fuel consumption.

  Therefore, it is necessary to accurately determine the deterioration of the oil. Conventionally, in order to judge the deterioration of lubricating oil, the fuel injection amount in the idle operation state is measured and compared with the idle fuel injection amount when the oil is new, and the fuel injection amount increases compared to when the oil is new. In such a case, a method for determining that the oil has deteriorated is known. It is based on the idea that oil degradation has resulted in increased friction during idle operation.

  However, an increase in friction during idling is a phenomenon caused by an abnormality or failure of the engine 1 such as damage to the piston ring or cylinder liner. Therefore, it may be difficult to determine whether it is caused by oil deterioration or engine abnormality only by detecting an increase in friction during idling. If it is erroneously determined that the oil has deteriorated when the engine is abnormal, there is a problem that an unnecessary oil change is performed and detection of the engine abnormality is delayed.

Here, since the temperature of the engine 1 is low in the light load operation state, lubrication is performed not in the mixed lubrication region but in the fluid lubrication region even if low viscosity oil is used. For this reason, when the oil viscosity further decreases due to oil deterioration, the friction is increased by entering the boundary lubrication region under the normal temperature environment, but entering the mixed lubrication region from the fluid lubrication region and reducing the friction. .

  In other words, a light load operating state in which a low temperature environment in which lubrication is performed in the non-degraded region is realized and a high load in which a high temperature environment in which lubrication is performed in the mixed lubrication region when non-deteriorated is realized. The change in the friction characteristics when the oil deteriorates tends to be different from the operating state.

  Therefore, in this embodiment, the friction is measured in two operating states in which the change tendency of the friction characteristics at the time of such oil deterioration is different, specifically, in a light load operation state and a high load operation state. Based on the relationship of the friction measured in the operating state, the oil deterioration determination is performed.

  Specifically, the friction measurement in the light load operation state is performed by injecting a small amount of fuel that does not affect the torque during the deceleration fuel cut operation, and measuring the rotation fluctuation torque at that time by the rotation fluctuation meter 15. Then, the difference between the torque that should be originally corresponding to the minute amount injection amount and the actual torque calculated based on the measured rotational fluctuation torque is calculated as the friction during the light load operation.

  In addition, the friction measurement in the high-load operation state is specifically performed by measuring the vehicle speed change before and after the elapse of a predetermined time (several seconds) by the vehicle speed sensor 20 during the acceleration transient operation, and the relationship between the acceleration and the fuel injection amount therebetween. Measure acceleration torque from Then, the difference between the torque that should be originally corresponding to the fuel injection amount during acceleration and the actual torque calculated based on the measured acceleration torque is calculated as the friction during high-load operation.

  And when both the friction at the time of light load driving | operation and the friction at the time of high load driving | running | working are below a predetermined permissible level, it determines with there being no oil deterioration.

  Further, when the friction during the light load operation is below the allowable level and the friction during the high load operation exceeds the allowable level, it is determined that the oil has deteriorated.

  Furthermore, if both the friction during light load operation and the friction during high load operation exceed the allowable level, it is determined that there is no oil deterioration but the engine 1 is abnormal.

  In this way, by considering the relationship between friction measured under two operating conditions with different friction characteristics when oil deteriorates, it is possible to distinguish between oil deterioration and engine abnormality, so that accurate oil determination is possible. At the same time, it is possible to quickly detect engine abnormality. Thereby, unnecessary oil exchange due to erroneous determination of oil deterioration can be suppressed.

  If it is determined that the oil has deteriorated, boundary lubrication is likely to be performed. Oil change may be encouraged. Further, when an engine abnormality is detected, the engine may be operated in the retreat travel mode when the engine is abnormal, and the driver may be notified of the engine abnormality by a notification means such as an instrument panel.

By performing reliable notification to the driver by such a notification means, accurate oil deterioration determination and engine abnormality detection by the system of the present embodiment can be linked to quick treatment by the driver.

  Further, in the system of the present embodiment, each cylinder 4 is provided with the in-cylinder pressure sensor 24. Therefore, when measuring the friction in the light load operation state and the high load operation state, the measured value of the in-cylinder pressure by the in-cylinder pressure sensor 24 is used. The indicated torque may be obtained based on the above, and the friction may be calculated as the difference between the indicated torque and the actual torque such as the rotational fluctuation torque during deceleration fuel cut micro injection and the acceleration torque during acceleration transient. By using the indicated torque, more accurate friction measurement can be performed.

  Note that the in-cylinder pressure sensor 24 is not necessarily provided when the friction measurement using the indicated torque is not performed.

  In the system of the present embodiment, since the tilt angle sensor 21 is provided, the deceleration fuel cut is performed based on the measured value by the tilt angle sensor 21 in the friction measurement in the light load operation state and the high load operation state. It is possible to correct the rotational fluctuation measured at the time of minute injection or to correct the acceleration measured at the acceleration transient.

  Specifically, at the time of downhill, for example, due to the action of gravity according to the vehicle weight and the inclination angle, there is a tendency that the rotational fluctuation and acceleration are shifted to a large value due to factors different from oil deterioration and engine abnormality. Therefore, the measured rotational fluctuation or acceleration is corrected to a smaller value as the tilt angle measured by the tilt angle sensor 21 is larger.

  On the other hand, when climbing, conversely, due to the action of gravity, the rotational fluctuation and acceleration tend to shift to small values due to factors different from oil deterioration and engine abnormality. Accordingly, the measured rotational fluctuation or acceleration is corrected to a larger value as the tilt angle measured by the tilt angle sensor 21 is larger.

  If the actual torque is calculated based on the rotation fluctuation torque and acceleration torque calculated using the rotation fluctuation and acceleration corrected in this way, and the friction is calculated based on this, the oil can be more accurately calculated. It becomes possible to grasp the friction caused by deterioration and engine abnormality.

  Note that the tilt angle sensor 21 is not necessarily provided when the rotation fluctuation and acceleration are not corrected based on the tilt angle.

  Next, the oil deterioration determination routine of the present embodiment will be described with reference to FIGS. 3 to 5 are flowcharts showing an oil deterioration determination routine of this embodiment.

  In step S101 of FIG. 3, the ECU 16 determines whether or not a deceleration fuel cut condition is satisfied. If it is determined that the deceleration fuel cut condition is satisfied (Yes), the ECU 16 proceeds to step S102. If it is determined that the deceleration fuel cut condition is not satisfied (No), the ECU 16 proceeds to step S106 in FIG.

  In step S102, the ECU 16 performs deceleration fuel cut control.

  In step S103, the ECU 16 injects a minute amount of fuel that does not affect the torque in the deceleration fuel cut control state, and measures the rotation fluctuation at that time by the rotation fluctuation meter 15. Based on the rotational fluctuation, the rotational fluctuation torque TL is calculated.

  In step S104, the ECU 16 calculates the indicated torque TL0 based on the measured value by the in-cylinder pressure sensor 24 when the minute fuel injection is performed.

  In step S105, the ECU 16 calculates a difference TL0−TL between the rotational fluctuation torque TL obtained in step S103 and the indicated torque TL0 obtained in step S104 as the friction TFL during light load operation.

  In step S106 of FIG. 4, the ECU 16 determines whether or not there is an acceleration request. If it is determined that there is an acceleration request (Yes), the ECU 16 proceeds to step S107. When it is determined that there is no acceleration request (No), the ECU 16 once ends the execution of this routine.

  In step S107, the ECU 16 performs acceleration control for increasing the fuel injection amount so as to output the required torque.

  In step S108, the ECU 16 calculates the acceleration of the vehicle accompanying the acceleration control. Then, an acceleration torque TH is calculated based on the calculated acceleration.

  In step S109, the ECU 16 calculates the indicated torque TH0 based on the value measured by the in-cylinder pressure sensor 24 when the acceleration control is performed.

  In step S110, the ECU 16 calculates a difference TH0-TH between the acceleration torque TH obtained in step S108 and the indicated torque TH0 obtained in step S109 as the friction TFH during high load operation.

  In step S111 of FIG. 5, the ECU 16 compares the friction TFL during light load operation obtained in step S105, the friction TFH during high load operation obtained in step S110, and the allowable friction value TFth.

  If both the friction TFL during light load operation and the friction TFH during high load operation are less than or equal to the allowable value TFth, the ECU 16 proceeds to step S112 and determines that there is no oil deterioration or engine abnormality.

  If the friction TFL during light load operation is less than or equal to the allowable value TFth and the friction TFH during high load operation is greater than the allowable value TFth, the ECU 16 proceeds to step S113, and determines that there is oil deterioration but there is no engine abnormality. When such a determination is made, the ECU 16 proceeds to step S114 to display a message prompting the driver to change oil and shift to a retreat traveling mode in which high load high rotation operation is prohibited.

  If the friction TFL during light load operation and the friction TFH during high load operation are both greater than the allowable value TFth, the ECU 16 proceeds to step S115 and determines that there is no oil deterioration but there is an engine abnormality. If such a determination is made, the ECU 16 proceeds to step S116 to display a notification that the engine is abnormal to the driver and to shift to the retreat travel mode when the engine is abnormal.

  By performing oil deterioration determination according to the above routine, it is possible to distinguish between oil deterioration and engine abnormality, so unnecessary oil replacement is performed when the engine is abnormal when the oil has not deteriorated. It is possible to suitably suppress the occurrence of a delay in engine abnormality detection due to erroneous determination of oil deterioration when the engine is abnormal.

  By accurately detecting the oil deterioration, it is possible to reliably suppress the occurrence of problems such as deterioration in fuel consumption due to oil deterioration even when low-viscosity oil is used as the lubricating oil. Therefore, it becomes possible to enjoy the fuel efficiency improvement effect by using low viscosity oil more reliably.

The above-described embodiment is an example for explaining the present invention, and various modifications can be made to the above-described embodiment without departing from the gist of the present invention. For example, in this example, 4
Although the example which applied this invention to the cylinder diesel engine was demonstrated, it can apply suitably also to the engine and gasoline engine from which the number of cylinders differs.

It is a figure which shows schematic structure of the intake system and exhaust system of the engine in an Example. It is a figure which shows the relationship between the state of lubricating oil, and friction. It is a flowchart showing the oil deterioration determination routine in an Example. It is a flowchart showing the oil deterioration determination routine in an Example. It is a flowchart showing the oil deterioration determination routine in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Intake passage 3 Exhaust passage 4 Cylinder 5 Variable nozzle vane 6 Intercooler 7 Air flow meter 8 Exhaust purification device 9 Throttle valve 10 Fuel injection valve 11 Compressor 12 Turbine 13 Turbocharger 14 Acceleration sensor 15 Rotational fluctuation meter 16 ECU
17 Intake manifold 18 Exhaust manifold 19 Accelerator opening sensor 20 Vehicle speed sensor 21 Inclination angle sensor 22 Accelerator pedal 24 In-cylinder pressure sensor

Claims (4)

Friction measuring means for measuring the friction of the internal combustion engine;
Based on the relationship of the measured friction, the friction measuring means measures the friction of the internal combustion engine under each of at least two different operating conditions that exhibit different friction characteristics when the lubricating oil of the internal combustion engine is deteriorated. Determining means for determining deterioration of the lubricating oil of the internal combustion engine;
An oil deterioration determination device for an internal combustion engine, comprising: In claim 1,
The determination means includes
Light load friction measured by the friction measuring means in a predetermined light load operating state of the internal combustion engine;
High load friction measured by the friction measuring means in a predetermined high load operating state of the internal combustion engine;
An oil deterioration determination device for an internal combustion engine, wherein the deterioration of the lubricating oil of the internal combustion engine is determined based on the relationship. In claim 2,
The determination means includes
The light load friction is below a predetermined allowable level, and
When the high load friction is larger than a predetermined allowable level,
An oil deterioration determination apparatus for an internal combustion engine, wherein the internal combustion engine lubricating oil is determined to be deteriorated. In claim 2,
The determination means includes
The light load friction is greater than a predetermined tolerance level, and
When the high load friction is larger than a predetermined allowable level,
An oil deterioration determination device for an internal combustion engine, which determines that the lubricating oil of the internal combustion engine has not deteriorated and that the internal combustion engine has an abnormality.

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