JP2017172524A - Engine oil abnormal consumption diagnostic system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an early diagnosis about an abnormal consumption of engine oil.SOLUTION: An engine oil abnormal consumption diagnosis device diagnoses an abnormal consumption of engine oil used at an engine 1. The engine 1 is configured to discharge exhaust gas after combustion to an exhaust passage 5 and discharges it outside through a catalyst 10. An air-fuel ratio sensor 46, an oxygen sensor 47 and an electronic control unit [ECU] 50 detect the maximum oxygen absorption amount Cmax of the catalyst 10. ECU 50 diagnoses an abnormal consumption of engine oil on the basis of the detected maximum oxygen absorption amount Cmax. In detail, ECU 50 includes a pre-set first threshold related to the maximum oxygen absorption amount Cmax and judges whether or not it is an abnormal consumption of engine oil by comparing an amount of change ΔCmax of the detected maximum oxygen absorption amount with the first threshold CT1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine oil abnormal consumption diagnosis device configured to diagnose an abnormal consumption of engine oil used in an engine.

  Engine oil used in the engine is stored in an oil pan, supplied for lubrication and cooling of each part of the engine, and configured to circulate in the engine. Further, a part of the engine oil enters the combustion chamber due to oil rising or the like, and is gradually consumed by being burned together with the fuel. Here, if the engine oil is abnormally consumed and the residual amount decreases, the engine performance may be adversely affected. Thus, it is desired to be able to diagnose abnormal consumption of engine oil.

  Conventionally, as this type of technique, for example, a technique described in Patent Document 1 below is known. This technology is a technology for avoiding harmful effects when the engine oil consumption is excessive (abnormal). Oil consumption detection means for detecting the speed of consumption of engine oil, and the detected oil consumption Load limiting means for executing control for limiting the engine load when the speed exceeds a predetermined reference value; An oil level sensor that detects the amount of engine oil in the oil pan and an electronic control unit (ECU) are provided as oil consumption detecting means. The ECU calculates the difference between the oil amount detected last time by the oil level sensor and the oil amount detected this time as the oil consumption amount. Here, in order to accurately detect the oil consumption, it is necessary to detect the oil amount in the oil pan under the same conditions every time.

JP2012-112300A

  However, in the technique described in Patent Document 1, since the difference between the oil amount detected last time and the current time is calculated as the oil consumption amount by the oil level sensor, in order to detect the speed of oil consumption, A period was needed. FIG. 7 is a graph showing the relationship between the cumulative travel distance of the vehicle and the oil consumption. As can be seen from this graph, the oil consumption is small from the travel start d0 to the first distance d1, and increases (becomes worse) after the first distance d1. In order to diagnose whether or not the oil consumption is abnormal after the first distance d1, for example, in FIG. 7, sampling of oil consumption is performed between the second distance d2 and the fourth distance d4. It is necessary to take a long interval. If the sampling interval is short, such as between the third distance d3 and the fourth distance d4, the diagnostic accuracy cannot be increased. Therefore, it has been difficult to diagnose abnormal consumption of engine oil at an early stage.

  In addition, since an oil level sensor is used to detect the engine oil level, it is highly dependent on the oil conditions (temperature, viscosity, oil return amount, etc.) at the time of detection, and the detection accuracy tends to be difficult to stabilize. there were. In addition, since it takes a certain amount of time to make the oil conditions uniform, it is difficult to diagnose an abnormal consumption of engine oil at an early stage.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an abnormal engine oil consumption diagnosis device that enables early diagnosis of abnormal oil consumption.

  In order to achieve the above object, an invention according to claim 1 is an abnormal engine oil consumption diagnosis device configured to diagnose an abnormal consumption of engine oil used in an engine, wherein the engine is a combustion engine. It is configured to discharge the later exhaust to the exhaust passage and to the outside through the catalyst provided in the exhaust passage, and to detect the maximum oxygen storage amount of the catalyst, and the detection means A diagnostic means for diagnosing abnormal consumption of engine oil based on the detected maximum oxygen storage amount, the diagnosis means including a preset reference value for the maximum oxygen storage amount, The purpose is to determine whether or not the engine oil is consumed abnormally by comparing the value related to the oxygen storage amount with a reference value.

  According to the configuration of the invention, the maximum oxygen storage amount of the catalyst is detected, and abnormal consumption of engine oil is diagnosed based on the maximum oxygen storage amount. Here, it has been confirmed that there is a correlation between the maximum oxygen storage amount of the catalyst and the consumption amount of engine oil. Then, it is determined whether or not the engine oil is abnormally consumed by comparing the detected value related to the maximum oxygen storage amount with a preset reference value. Therefore, it is not necessary to directly detect the engine oil level to diagnose abnormal consumption of engine oil, and the diagnosis does not depend on the oil conditions (temperature, viscosity, oil return amount, etc.), and the oil conditions are stabilized. No need to wait.

  In order to achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the reference value is set as a change amount of the maximum oxygen storage amount over a predetermined period, and the diagnostic means is detected. The purpose is to determine that the engine oil is abnormally consumed when the amount of change in the maximum oxygen storage amount over a predetermined period exceeds a reference value.

  According to the configuration of the invention, in addition to the operation of the invention according to claim 1, since the change amount of the maximum oxygen storage amount of the catalyst is compared with the reference value, the normal value related to the change of the maximum oxygen storage amount is obtained as data. There is no need to have as.

  In order to achieve the above object, according to a third aspect of the present invention, in the first aspect of the present invention, the reference value is set as a free difference from the normal value of the maximum oxygen storage amount, and the diagnostic means is detected. The purpose is to determine that the engine oil is abnormally consumed when the liberation difference from the normal value of the maximum oxygen storage amount is greater than or equal to the reference value.

  According to the configuration of the invention, in addition to the operation of the invention according to claim 1, since the liberation difference with respect to the normal value of the maximum oxygen storage amount of the catalyst is compared with the reference value, the maximum oxygen storage is compared with the normal value. A relative judgment can be made about the change of the quantity.

  In order to achieve the above object, according to a fourth aspect of the present invention, in the second aspect of the present invention, the engine is mounted on the vehicle, and for a predetermined period of time, the accumulated travel distance of the vehicle or the heat of the catalyst. The purpose is to be set based on the history.

  According to the configuration of the invention described above, in addition to the operation of the invention according to claim 2, abnormal consumption of engine oil is diagnosed reflecting the substantial use period of the catalyst.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the third aspect of the present invention, the engine is mounted on the vehicle, and the normal value is the cumulative travel distance of the vehicle or the heat of the catalyst. The purpose is to be set according to the history.

  According to the configuration of the invention, in addition to the action of the invention according to claim 3, the normal value of the maximum oxygen storage amount is set reflecting the substantial use period of the catalyst.

  According to the first aspect of the present invention, abnormal consumption of engine oil can be diagnosed early.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the configuration of the diagnostic apparatus can be simplified by the amount that does not have normal values as data.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1, it is possible to accurately diagnose abnormal consumption of engine oil by the amount of comparing the maximum oxygen storage amount with the normal value.

  According to the invention described in claim 4, in addition to the effect of the invention described in claim 2, it is possible to accurately diagnose abnormal consumption of engine oil.

  According to the invention described in claim 5, in addition to the effect of the invention described in claim 3, abnormal consumption of engine oil can be diagnosed more accurately.

1 is a schematic configuration diagram illustrating an engine system according to a first embodiment. The graph which shows the relationship of the change of the oil consumption amount and the maximum oxygen storage amount with respect to 1st Embodiment with respect to an integral travel distance or the thermal history of a catalyst. The flowchart which concerns on 1st Embodiment and shows the content of engine oil abnormal consumption diagnostic control. The graph which shows the relationship of the change of the oil consumption amount and the maximum oxygen storage amount with respect to 2nd Embodiment with respect to an integral travel distance or the thermal history of a catalyst. The map which shows the relationship of the normal value which concerns on 2nd Embodiment, and relates to the maximum travel distance or the thermal history of a catalyst with respect to the maximum oxygen storage amount. The flowchart which concerns on 2nd Embodiment and shows the content of engine oil abnormal consumption diagnostic control. The graph which concerns on a prior art example and shows the relationship between an integrated travel distance and oil consumption.

<First Embodiment>
Hereinafter, a first embodiment of the engine oil abnormal consumption diagnosis device according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an engine system in this embodiment. In this embodiment, the engine 1 mounted on the vehicle is a four-cycle reciprocating engine and includes four cylinders 2 and a crankshaft 3. The engine 1 is provided with an intake passage 4 and an exhaust passage 5. An air cleaner 6, an electronic throttle device 7, and a surge tank 8 are provided in the intake passage 4 from the upstream side. The electronic throttle device 7 includes a throttle valve 9 that is opened and closed by a motor 31 and a throttle sensor 41 for detecting an opening degree (throttle opening degree) TA of the throttle valve 9. The exhaust passage 5 is provided with a catalyst 10 for purifying exhaust gas. That is, the engine 1 is configured to discharge the exhaust after combustion to the exhaust passage 5 and to the outside through the catalyst 10 provided in the exhaust passage 5. In this embodiment, the catalyst 10 is composed of a well-known three-way catalyst.

  The engine 1 includes a cylinder block 11 and a cylinder head 12. In the cylinder block 11, a piston 13 is provided for each cylinder 2. Each piston 13 is connected to the crankshaft 3 via a connecting rod 14. Each cylinder 2 includes a combustion chamber 15. An intake port 16 and an exhaust port 17 communicating with each combustion chamber 15 are formed in the cylinder head 12. Each intake port 16 communicates with the intake passage 4. Each exhaust port 17 communicates with the exhaust passage 5. Each intake port 16 is provided with an intake valve 18, and each exhaust port 17 is provided with an exhaust valve 19. Each intake valve 18 and each exhaust valve 19 are linked to the rotation of the crankshaft 3, that is, linked to the vertical movement of each piston 13, and thus a series of operating strokes (intake stroke, compression stroke, expansion) of the engine 1. It is driven to open and close by a valve mechanism 21 including a camshaft 20 and the like in conjunction with the stroke and the exhaust stroke).

  The cylinder head 12 is provided with an injector 32 that directly injects fuel into each combustion chamber 15 corresponding to each cylinder 2. Each injector 32 is configured to inject and supply fuel supplied from a fuel supply device (not shown) to each corresponding combustion chamber 15. In each combustion chamber 15, a combustible air-fuel mixture is formed by the fuel injected from the injector 32 and the intake air introduced from the intake passage 4 in the intake stroke.

  The cylinder head 12 is provided with a spark plug 33 in each combustion chamber 15 corresponding to each cylinder 2. Each spark plug 33 receives the ignition signal output from the ignition coil 34 and performs a spark operation. Both parts 33 and 34 constitute an ignition device that ignites a combustible air-fuel mixture formed in each combustion chamber 15. The combustible air-fuel mixture in each combustion chamber 15 explodes and burns by the spark operation of each spark plug 33 in the compression stroke, and the expansion stroke passes. Exhaust gas after combustion is discharged from each combustion chamber 15 to the outside through the exhaust port 17, the exhaust passage 5 and the catalyst 10 in the exhaust stroke. With combustion of the combustible air-fuel mixture in each combustion chamber 15, each piston 13 moves up and down, a series of operation strokes advance, and the crankshaft 3 rotates, whereby power is obtained in the engine 1.

  As shown in FIG. 1, various sensors 41 to 47 provided in the engine 1 detect the operating state of the engine 1. An accelerator sensor 42 is provided on the accelerator pedal 27 provided in the driver's seat. The accelerator sensor 42 detects the depression angle of the accelerator pedal 27 as the accelerator opening ACC, and outputs an electric signal corresponding to the detected value. The water temperature sensor 43 provided in the engine 1 detects the temperature (cooling water temperature) THW of the cooling water flowing inside the cylinder block 11 and outputs an electric signal corresponding to the detected value. The rotational speed sensor 44 provided in the engine 1 detects the rotational position (crank angle) and rotational speed (engine rotational speed) NE of the crankshaft 3, and outputs an electrical signal corresponding to the detected value. The sensor 44 is configured to detect the rotation of the timing rotor 28 fixed to one end of the crankshaft 3 for each predetermined angle. The intake pressure sensor 45 provided in the surge tank 8 detects the intake pressure PM in the surge tank 8 downstream of the electronic throttle device 7 and outputs an electrical signal corresponding to the detected value. The air-fuel ratio sensor 46 provided in the exhaust passage 5 upstream from the catalyst 10 detects the air-fuel ratio A / F in the exhaust discharged to the exhaust passage 5 and outputs an electric signal corresponding to the detected value. The oxygen sensor 47 provided in the exhaust passage 5 downstream from the catalyst 10 detects the oxygen concentration Ox in the exhaust gas that has passed through the catalyst 10 and outputs an electrical signal corresponding to the detected value.

  The engine system includes an electronic control unit (ECU) 50 that performs various controls. Various sensors 41 to 47 are connected to the ECU 50. The ECU 50 is connected to a motor 31, injectors 32, and ignition coils 34, respectively.

  In this embodiment, the ECU 50 receives signals output from the various sensors 41 to 47, and performs the fuel injection control and the ignition timing control based on these signals, so that the motor 31, the injectors 32, and the ignition coils 34 are executed. Each is controlled. Further, the ECU 50 executes engine oil abnormal consumption diagnosis control based on signals output from the air-fuel ratio sensor 46 and the oxygen sensor 47. In this embodiment, the air-fuel ratio sensor 46, the oxygen sensor 47, and the ECU 50 constitute an example of detection means for detecting the maximum oxygen storage amount Cmax of the catalyst 10. The ECU 50 corresponds to an example of a diagnostic unit for diagnosing abnormal consumption of engine oil based on the detected maximum oxygen storage amount Cmax.

  As is well known, the ECU 50 includes a central processing unit (CPU), various memories, an external input circuit, an external output circuit, and the like. The memory stores a predetermined control program related to various controls of the engine 1. The CPU executes the various controls described above based on a predetermined control program based on detection signals of the various sensors 41 to 47 input via the input circuit.

  Here, the fuel injection control is to control the fuel injection amount and the injection timing by each injector 32 in accordance with the operating state of the engine 1. The ignition timing control is to control the ignition timing by each ignition plug 33 by controlling each ignition coil 34 according to the operating state of the engine 1.

  The abnormal engine oil consumption diagnosis control is to detect the maximum oxygen storage amount Cmax of the catalyst 10 based on signals from the air-fuel ratio sensor 46 and the oxygen sensor 47, and to detect the engine oil based on the detected maximum oxygen storage amount Cmax. It is to diagnose abnormal consumption. In this embodiment, phosphorus (element symbol: P) added in advance to the engine oil flows to the catalyst 10 together with the exhaust gas, so that the poisoning situation given to the catalyst 10 changes, and the catalyst 10 is changed by the change in the poisoning situation. It is assumed that the maximum oxygen storage amount Cmax changes. That is, it is assumed that the maximum oxygen storage amount Cmax of the catalyst 10 decreases as the consumption amount of engine oil increases. In this embodiment, abnormal consumption of engine oil is diagnosed using the correlation between the engine oil consumption and the maximum oxygen storage amount Cmax.

  FIG. 2 is a graph showing the relationship between changes in engine oil consumption (oil consumption) and maximum oxygen storage amount Cmax with respect to the vehicle's cumulative travel distance or the thermal history of the catalyst 10. In FIG. 2, a solid line and a broken line indicate changes in the maximum oxygen storage amount Cmax, a solid line indicates a case where the change is normal, and a broken line indicates a case where the change is abnormal. A thick line and a thick broken line indicate a change in oil consumption, a thick line indicates a case where the change is normal, and a thick broken line indicates a case where the change is abnormal. FIG. 2 shows that there is a correlation between the change (decrease) in the maximum oxygen storage amount Cmax and the change (increase) in the oil consumption. That is, even if it is normal, after a certain amount of cumulative travel distance of the vehicle or thermal history of the catalyst has passed, the oil consumption increases due to deterioration of each part of the vehicle, etc. The maximum oxygen storage amount Cmax decreases. Therefore, in the case of an abnormality (in other words, when the oil consumption is relatively large compared to the normal amount of change in the oil consumption for a predetermined period), the maximum oxygen storage amount Cmax is set to correspond to this. The change amount ΔCmax during the predetermined period is relatively large as compared with the normal case.

  Next, engine oil abnormal consumption diagnosis control will be described. FIG. 3 shows the contents from a flowchart.

  When the process proceeds to this routine, in step 100, the ECU 50 calculates (detects) the maximum oxygen storage amount Cmax. Here, the ECU 50 can calculate the maximum oxygen storage amount Cmax of the catalyst 10 by a known method. For example, the ECU 50 performs active control that reverses “rich” and “lean” of the output of the air-fuel ratio sensor 46 (air-fuel ratio A / F) each time the output of the oxygen sensor 47 is reversed, thereby maximizing oxygen storage. The quantity Cmax can be determined. Regarding the calculation method of the maximum oxygen storage amount Cmax, for example, Japanese Patent Application Laid-Open Nos. 2006-2491979 and 2012-112334 can be referred to.

  Next, in step 110, the ECU 50 sets the previously calculated "change amount ΔCmax (n) of the current maximum oxygen storage amount" as "the previous change amount ΔCmax (n-1) of the maximum oxygen storage amount". Store in memory. The change amount ΔCmax of the maximum oxygen storage amount will be described later.

  Next, in step 120, the ECU 50 determines whether or not a predetermined period based on the heat history has elapsed since the previous determination. Here, “thermal history” means the cumulative thermal history of the catalyst 10 (accumulated value of the catalyst simulated temperature), and the ECU 50 can calculate this thermal history by a separate routine. In this embodiment, the predetermined period of the present invention is set based on the thermal history of the catalyst 10. The ECU 50 proceeds to step 130 when the determination result is affirmative, and returns the process to step 100 when the determination result is negative.

  In step 130, the ECU 50 determines whether or not the calculation of the current maximum oxygen storage amount Cmax has been completed. The ECU 50 proceeds to step 140 when the determination result is affirmative, and returns the process to step 100 when the determination result is negative.

  In step 140, the ECU 50 sequentially stores the calculated maximum oxygen storage amount Cmax in the memory. Thus, the current maximum oxygen storage amount Cmax (n), the previous maximum oxygen storage amount Cmax (n-1), the previous maximum oxygen storage amount Cmax (n-2),... Will be.

  Next, in step 150, the ECU 50 subtracts the current maximum oxygen storage amount Cmax (n) from the previous maximum oxygen storage amount Cmax (n−1), so that “this time The maximum change amount ΔCmax (n) of the maximum oxygen storage amount is calculated.

  Next, in step 160, the ECU 50 determines whether or not the calculated current change amount ΔCmax (n) is greater than or equal to a predetermined first threshold value CT1. The first threshold value CT1 corresponds to an example of the reference value of the present invention, and is stored in advance in the memory of the ECU 50. If this determination result is affirmative, the ECU 50 proceeds to step 170, and if this determination result is negative, the ECU 50 returns the process to step 100.

  In step 170, the ECU 50 temporarily determines that the engine oil is abnormally consumed (oil abnormal consumption). The provisional determination is not a final determination.

  Next, in step 180, the ECU 50 determines whether or not the previous change amount ΔCmax (n−1) is equal to or greater than a predetermined first threshold value CT1. The ECU 50 proceeds to step 190 when the determination result is affirmative, and returns the process to step 100 when the determination result is negative.

  In step 190, the ECU 50 determines that the oil is abnormally consumed. That is, as shown in FIG. 2, the ECU 50 calculates the current maximum oxygen storage amount Cmax (n), and the previous maximum oxygen storage amount Cmax (n-1) of the current maximum oxygen storage amount Cmax (n). Is calculated as a current change amount ΔCmax (n). When the ECU 50 determines that the current change amount ΔCmax (n) is equal to or greater than the first threshold value CT1 and temporarily determines that the oil is abnormally consumed, the previous change amount ΔCmax (n−1) (the previous maximum oxygen storage amount Cmax ( When the difference between the maximum oxygen storage amount Cmax (n-2) of n-1) and the previous time is also abnormal, the main determination is made as abnormal oil consumption. The ECU 50 can store this determination of abnormal oil consumption in a memory, or can execute predetermined notification control to notify the driver that abnormal oil consumption has occurred.

  According to the above control, the ECU 50 stores the preset first threshold value CT1 (reference value) related to the maximum oxygen storage amount Cmax in the memory and includes the calculated (detected) value related to the calculated maximum oxygen storage amount Cmax. By comparing (change amounts ΔCmax (n), ΔCmax (n−1)) with the first threshold value CT1, it is determined whether or not the engine oil is abnormally consumed. Specifically, the first threshold value CT1 that is a reference value is set as a change amount of the maximum oxygen storage amount Cmax in a predetermined period. The ECU 50 determines that the engine oil is abnormal when both the current change amount ΔCmax (n) and the previous change amount ΔCmax (n−1) of the calculated maximum oxygen storage amount Cmax are equal to or greater than the first threshold value CT1. It comes to judge that it is consumption.

  According to the engine oil abnormality consumption diagnosis device of this embodiment described above, the maximum oxygen storage amount Cmax of the catalyst 10 is calculated (detected) by the air-fuel ratio sensor 46, the oxygen sensor 47 and the ECU 50, and the maximum oxygen storage amount Cmax. Based on this, abnormal consumption of engine oil is diagnosed. Here, it has been confirmed that there is a correlation between the maximum oxygen storage amount Cmax of the catalyst 10 and the consumption amount of the engine oil. Then, a value (change amount ΔCmax (n), ΔCmax (n−1)) related to the calculated (detected) maximum oxygen storage amount Cmax is compared with a preset reference value (first threshold value CT1). Thus, the ECU 50 determines whether or not the engine oil is abnormally consumed. Therefore, in order to diagnose abnormal consumption of engine oil, it is not necessary to directly detect the engine oil amount with an oil level sensor or the like, and the diagnosis does not depend on oil conditions (temperature, viscosity, oil return amount, etc.) There is no need to wait for oil conditions to stabilize. For this reason, abnormal consumption of engine oil can be diagnosed early.

  In this embodiment, since the change amount ΔCmax of the maximum oxygen storage amount Cmax of the catalyst 10 is compared with the first threshold value CT1, it is not necessary to have a normal value related to the change of the maximum oxygen storage amount Cmax as data in the memory of the ECU 50. . For this reason, the structure of this diagnostic apparatus can be simplified by the amount which does not have a normal value as data.

  In this embodiment, since the predetermined period for calculating the change amount ΔCmax of the maximum oxygen storage amount Cmax is set based on the thermal history of the catalyst 10, the engine oil reflects the substantial use period of the catalyst 10. Abnormal consumption of is diagnosed. For this reason, it is possible to accurately diagnose abnormal consumption of engine oil.

  Here, in the engine 1, the engine oil is discharged from the combustion chamber 15 to the exhaust passage 5 with a slight reciprocation of the piston 13. At this time, if phosphorus in the discharged engine oil is accumulated in the catalyst 10, the catalyst 10 is poisoned and deteriorates. The phosphorus adhesion amount of the catalyst 10 after the durability test is large in the vicinity of the inlet side end face of the catalyst 10 and is small in the downstream side. It is thought that phosphorus collides with and adheres to the walls of the catalyst 10 due to the turbulent flow generated on the upstream side of the catalyst 10. This is thought to cause pore clogging and precious metal coating, resulting in a decrease in catalyst purification capacity. This catalyst purification capacity can be expressed by the maximum oxygen storage amount Cmax. In this embodiment, the amount of change ΔCmax (n) of the current maximum oxygen storage amount Cmax (n) with respect to the previous maximum oxygen storage amount Cmax (n−1) is repeated twice or more than the first threshold value CT1. When this occurs, it is determined that oil consumption is abnormal. That is, when the two changes ΔCmax (n) and ΔCmax (n−1) of the current time and the previous time are abnormal oil consumption, the main determination is made as abnormal oil consumption. Thereby, erroneous determination of abnormal oil consumption can be prevented. Since poisoning of the catalyst 10 includes poisoning of sulfur (element symbol: S) in addition to poisoning of phosphorus, erroneous determination due to sulfur poisoning can be avoided.

Second Embodiment
Next, a second embodiment of the engine oil abnormal consumption diagnosis device according to the present invention will be described in detail with reference to the drawings.

  In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and different points are mainly described.

  This embodiment differs from the first embodiment in terms of the contents of engine oil abnormal consumption diagnosis control. FIG. 4 is a graph showing the relationship between changes in the oil consumption amount and the maximum oxygen storage amount Cmax with respect to the cumulative travel distance of the vehicle or the thermal history of the catalyst 10. In FIG. 4, a solid line and a broken line indicate changes in the maximum oxygen storage amount Cmax, a solid line indicates a case where the change is normal (normal value CS), and a broken line indicates an example where the change is abnormal. A thick line and a thick broken line indicate a change in oil consumption, a thick line indicates a case where the change is normal, and a thick broken line indicates a case where the change is abnormal. In FIG. 4, the correlation between the change (decrease) in the maximum oxygen storage amount Cmax and the change (increase) in the oil consumption is the same as that in FIG. Accordingly, as shown in FIG. 4, the maximum oxygen storage amount Cmax is released from the normal case (solid line: normal value CS) when it is abnormal (broken line). By determining the magnitude of this free difference ΔCS, it is possible to determine whether or not the maximum oxygen storage amount Cmax is abnormal, that is, whether or not the oil consumption is abnormal. In this embodiment, the relationship of the normal value CS related to the maximum oxygen storage amount Cmax with respect to the cumulative travel distance or the thermal history of the catalyst 10 is preset as a map as shown in FIG. 5, and the map is stored in the memory of the ECU 50. Yes. This normal value CS shows the same value as the normal value of the maximum oxygen storage amount Cmax in FIG.

  FIG. 6 is a flowchart showing the contents of the engine oil abnormal consumption diagnosis control. In this flowchart, the contents of steps 115, 155, 165 and 185 are different from the contents of steps 110, 150, 160 and 180 in the flowchart of FIG. 3, and the contents of other steps 100, 120 to 140, 170 and 190 are as follows. It is the same as that of FIG.

  When the process shifts to this routine, after executing the process of step 100, in step 115, the ECU 50 sets the present free difference ΔCS (n) calculated last time as the previous free difference ΔCS (n−1). Store in memory. This free difference ΔCS will be described later.

  Thereafter, after executing the processing of step 120 to step 140, in step 155, the ECU 50 subtracts the current maximum oxygen storage amount Cmax (n) from the current normal value CS (n), thereby determining the current maximum oxygen concentration. The free difference ΔCS (n) from the normal value CS of the occlusion amount is calculated. This free difference ΔCS (n) represents the degree of abnormal consumption of engine oil.

  Next, in step 165, the ECU 50 determines whether or not the calculated current difference ΔCS (n) is greater than or equal to a predetermined second threshold value CT2. The second threshold value CT2 corresponds to an example of the reference value of the present invention, and is stored in the memory of the ECU 50. If this determination result is affirmative, the ECU 50 proceeds to step 170, and if this determination result is negative, the ECU 50 returns the process to step 100.

  After tentatively determining that the oil is abnormally consumed in step 170, the ECU 50 determines in step 185 whether or not the previous difference ΔCS (n−1) is equal to or greater than a predetermined second threshold value CT2. If this determination result is affirmative, the ECU 50 proceeds to step 190 and makes a main determination that the oil is abnormally consumed. If this determination is negative, the ECU 50 returns the process to step 100.

  According to the above control, the ECU 50 stores the preset second threshold value CT2 (reference value) related to the maximum oxygen storage amount Cmax in the memory and includes the calculated (detected) value related to the calculated maximum oxygen storage amount Cmax. By comparing (free difference ΔCS (n), ΔCS (n−1)) with the second threshold value CT2, it is determined whether or not the engine oil is abnormally consumed. Specifically, the second threshold value CT2 is set as a free difference with respect to the normal value CS of the maximum oxygen storage amount Cmax. The ECU 50 determines that the engine oil is abnormally consumed when both the calculated current difference ΔCS (n) and the previous time difference ΔCS (n−1) are equal to or greater than the second threshold value CT2. It is like that.

  According to the engine oil abnormal consumption diagnosis device of this embodiment described above, abnormal consumption of engine oil is diagnosed based on the maximum oxygen storage amount Cmax of the catalyst 10. Then, the value (free difference ΔCS (n), ΔCS (n−1)) related to the calculated maximum oxygen storage amount Cmax is compared with a preset reference value (second threshold value CT2), whereby the engine The ECU 50 determines whether or not the oil is abnormally consumed. Therefore, in order to diagnose abnormal consumption of engine oil, it is not necessary to directly detect the engine oil amount with an oil level sensor or the like, and the diagnosis does not depend on oil conditions (temperature, viscosity, oil return amount, etc.) There is no need to wait for oil conditions to stabilize. For this reason, abnormal consumption of engine oil can be diagnosed early.

  According to this embodiment, since the release difference ΔCS of the maximum oxygen storage amount Cmax of the catalyst 10 with respect to the normal value CS is compared with the second threshold value CT2, relative to the change of the maximum oxygen storage amount Cmax from the comparison with the normal value CS. Judgment is possible. For this reason, abnormal consumption of engine oil can be accurately diagnosed by the amount of comparison of the maximum oxygen storage amount Cmax with the normal value CS.

  In this embodiment, since the normal value CS is set according to the cumulative travel distance of the vehicle or the thermal history of the catalyst, the normal value CS of the maximum oxygen storage amount Cmax reflects the substantial use period of the catalyst 10. Is set. In this sense, abnormal consumption of engine oil can be diagnosed more accurately.

  Note that the present invention is not limited to the above-described embodiments, and a part of the configuration can be changed as appropriate without departing from the spirit of the invention.

  (1) In each of the embodiments described above, the predetermined period for calculating the maximum oxygen storage amount Cmax is set based on the thermal history of the catalyst 10, but it can also be set based on the accumulated travel distance of the vehicle instead of the thermal history.

  (2) In each of the above-described embodiments, the engine oil is determined to be abnormal when the abnormal oil consumption is determined twice. However, the abnormal engine oil is determined based on the single determination of the abnormal oil consumption. It can also be configured to determine consumption.

  The present invention can be used for diagnosis of abnormal consumption of engine oil in an engine system having a catalyst in an exhaust passage.

1 engine 5 exhaust passage 10 catalyst 46 air-fuel ratio sensor (detection means)
47 Oxygen sensor (detection means)
50 ECU (detection means, diagnosis means)
Cmax Maximum oxygen storage amount ΔCmax Change amount (maximum oxygen storage amount)
CT1 first threshold (reference value)
CT2 Second threshold (reference value)
CS normal value ΔCS liberation difference

Claims (5)

An engine oil abnormal consumption diagnosis device configured to diagnose abnormal consumption of engine oil used in an engine,
The engine is configured to discharge exhaust gas after combustion to an exhaust passage and to discharge outside through a catalyst provided in the exhaust passage;
Detection means for detecting the maximum oxygen storage amount of the catalyst;
Diagnostic means for diagnosing abnormal consumption of the engine oil based on the maximum oxygen storage amount detected by the detection means, the diagnosis means comprising a preset reference for the maximum oxygen storage amount And determining whether or not the engine oil is abnormally consumed by comparing the detected value relating to the maximum oxygen storage amount with the reference value. . The reference value is set as a change amount of the maximum oxygen storage amount for a predetermined period,
The diagnostic means determines that the engine oil is abnormally consumed when the detected amount of change in the predetermined period of the maximum oxygen storage amount is equal to or greater than the reference value. The engine oil abnormal consumption diagnosis device described. The reference value is set as a free difference with respect to a normal value of the maximum oxygen storage amount,
The diagnostic means determines that the consumption of the engine oil is abnormal when the difference between the detected maximum oxygen storage amount and the normal value is equal to or greater than the reference value. The engine oil abnormal consumption diagnosis device described. The engine is mounted on a vehicle,
3. The engine oil abnormal consumption diagnosis device according to claim 2, wherein the predetermined period is set based on an accumulated travel distance of the vehicle or a thermal history of the catalyst. The engine is mounted on a vehicle,
4. The engine oil abnormal consumption diagnosis device according to claim 3, wherein the normal value is set according to an accumulated travel distance of the vehicle or a thermal history of the catalyst.

Images