JP2007127076A - Abnormality diagnosis apparatus for in-cylinder internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To diagnose abnormality of a fuel system by appropriately grasping influence of oil dilution by fuel in a direct injection engine provided with a blow-by gas restoration device (PCV, Positive Crankcase Ventilation device). <P>SOLUTION: An engine EUC executes a program including a step S120 monitoring fuel system OBD (S100) and detecting A/F correction quantity 1 if A/F correction quantity is threshold value or more (Yes in S110), a step S130 reducing fuel pressure, a step S140 detecting A/F correction quantity 2 after fuel pressure reduction, a step S150 calculating A/F correction quantity difference, a step S170 judging that an injector is abnormal and lighting MIL when correction quantity difference is injector abnormality judging threshold value or more (Yes in S160), and a step S180 judging that a reason why the injector is normal and A/F correction quantity gets to the threshold value or more is that oil composition diluted by fuel is returned to an intake passage by the PCV device when the correction quantity difference is less than the injector abnormality judging threshold value (No in S160) and restraining from lighting MIL. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an abnormality diagnosis device that determines an abnormality of a fuel injection system based on an air-fuel ratio correction amount of air-fuel ratio feedback control, and more particularly to an abnormality diagnosis device that is preferably applied to a direct injection internal combustion engine.

In general, an exhaust system of an internal combustion engine is provided with a catalytic converter for purifying harmful components in exhaust gas. As this catalytic converter, a three-way catalytic converter is widely used, which oxidizes carbon monoxide (CO) and unburned hydrocarbon (HC), which are three components in exhaust gas, and nitrogen oxide (NOx). Is converted into carbon dioxide (CO ₂ ), water vapor (H ₂ O), and nitrogen (N ₂ ).

  The purification characteristics of the three-way catalytic converter depend on the air-fuel ratio of the air-fuel mixture formed in the combustion chamber, and the three-way catalytic converter functions most effectively when it is close to the stoichiometric air-fuel ratio. This is because if the air-fuel ratio is lean and the amount of oxygen in the exhaust gas is large, the oxidizing action becomes active but the reducing action becomes inactive, and if the air-fuel ratio is rich and the amount of oxygen in the exhaust gas is small, On the contrary, the reducing action becomes active, but the oxidizing action becomes inactive, and it is not possible to purify all of the above-mentioned harmful three components satisfactorily. Therefore, an internal combustion engine having a three-way catalytic converter is provided with an output linear oxygen sensor in its exhaust passage, and the air-fuel ratio of the air-fuel mixture in the combustion chamber is converted to the stoichiometric air-fuel ratio by using the oxygen concentration measured thereby. The air-fuel ratio feedback control is performed so that the stoichiometric air fuel ratio (hereinafter sometimes referred to as stoichiometric) may be obtained.

  In the situation where such air-fuel ratio feedback control is being performed, for example, if any abnormality occurs in the fuel injection system including the fuel injection valve, it is difficult to supply a predetermined amount of fuel to the internal combustion engine. The air-fuel ratio tends to greatly deviate from the target air-fuel ratio, which may cause deterioration of exhaust gas components. When such an abnormality occurs, the feedback correction amount for making the actual air-fuel ratio coincide with the target air-fuel ratio, that is, the air-fuel ratio correction amount becomes a very large value.

  Therefore, when executing the air-fuel ratio feedback control, the air-fuel ratio correction amount is monitored. When the air-fuel ratio correction amount increases excessively, it is determined that an abnormality has occurred in the fuel injection system. I am trying to diagnose any abnormalities.

  Further, the internal combustion engine is provided with a blow-by gas reduction device for processing gas leaking from the cylinder into the crankcase, so-called blow-by gas. Since blow-by gas is strongly acidic, it may cause rust on the metal part of the engine body or deteriorate the lubricating oil (engine oil) present in the engine body. This blow-by gas reduction device introduces fresh air into the engine body from the outside (more precisely, an air cleaner provided in the intake system, etc.), circulates it inside the crankcase, and finally returns it to the intake system By performing this, the blow-by gas is processed without being discharged to the outside.

A cylinder injection type internal combustion engine having a fuel injection valve for directly injecting fuel into the combustion chamber of the internal combustion engine is also known. In such an internal combustion engine, when the internal combustion engine is at a low load, such as during idling, the fuel is injected into the cylinder during the compression stroke to perform weak stratified combustion, and during a high load, the fuel is injected into the cylinder during the intake stroke. The in-cylinder injection type internal combustion engine, which achieves both low fuel consumption and high output by performing uniform combustion by injecting into the cylinder, is different from the intake port injection type internal combustion engine. The problem is that the engine oil is diluted by the fuel because the distance between the nozzle hole of the valve and the inner peripheral surface of the cylinder is extremely short and the injected fuel can collide directly with the inner peripheral surface of the cylinder. Can do.

  That is, when the engine is cold, the atomization of fuel in the cylinder is difficult to promote, so that a portion of the injected fuel is not burned and remains attached to the cylinder inner circumferential surface (cylinder inner circumferential surface). become. The fuel adhering to the cylinder inner peripheral surface is mixed with the engine oil adhering to the cylinder inner peripheral surface for lubrication of the engine piston. As a result, engine oil is diluted with fuel.

  The engine oil on the cylinder inner peripheral surface diluted with fuel in this way is scraped off as the engine piston moves up and down, and returns to the crankcase (more precisely, an oil pan formed as a part thereof). After that, the engine piston and the like are again used for lubricating the internal combustion engine. Therefore, when the dilution of the engine oil with such fuel frequently occurs, the ratio of the fuel mixed in the engine oil in the crankcase, in other words, the whole engine oil used for lubricating the internal combustion engine gradually increases. .

  When the ratio of the fuel contained in the engine oil increases in this way, a large amount of fuel evaporates from the engine oil accordingly, so that the fuel concentration of the blow-by gas greatly increases. In particular, when the amount of fuel injection is relatively small, such as when the engine is under low load, when blow-by gas having a significantly increased fuel concentration is introduced into the intake system, the air-fuel ratio is attributed to this. The air-fuel ratio correction amount of the feedback control is excessively increased, and there is a possibility that a misdiagnosis indicating an abnormality is made although no abnormality has occurred in the fuel injection system.

  Japanese Patent Application Laid-Open No. 2003-332047 (Patent Document 1) is caused by dilution of engine oil due to fuel adhesion on the inner circumferential surface of a fuel injection system when diagnosing abnormality of the fuel injection system based on the air-fuel ratio correction amount of air-fuel ratio feedback control. Disclosed is an abnormality diagnosis device for a direct injection internal combustion engine that can suppress erroneous diagnosis as much as possible. The abnormality diagnosing device disclosed in Patent Document 1 is a determination means for determining an abnormality of the fuel injection system based on an air-fuel ratio correction amount of air-fuel ratio feedback control obtained based on a deviation tendency between an actual air-fuel ratio and a target air-fuel ratio. An abnormality diagnosis apparatus for a direct injection internal combustion engine comprising: an estimation means for estimating a dilution degree of the whole engine oil used for lubrication of the internal combustion engine, and a condition that the estimated dilution degree is large And a limiting unit for limiting the determination operation that the determination unit is abnormal.

According to this abnormality diagnosis apparatus for a direct injection internal combustion engine, the determination means determines abnormality of the fuel injection system based on the air-fuel ratio correction amount of the air-fuel ratio feedback control. The estimating means estimates the degree of dilution of the entire engine oil used for lubricating the internal combustion engine. Then, when the estimated degree of dilution of the entire engine oil is large and therefore the amount of fuel evaporation from the engine oil is increasing, the limiting means limits the determination operation that the determining means is abnormal. That is, in this case, it is difficult to determine that there is an abnormality compared to when the degree of dilution is small. Therefore, it is possible to suppress as much as possible a misdiagnosis caused by dilution of the engine oil in the abnormality diagnosis of the fuel injection system based on the air-fuel ratio correction amount of the air-fuel ratio feedback control.
Japanese Patent Laid-Open No. 2003-332047

  However, according to the abnormality diagnosis device disclosed in Patent Document 1 described above, the degree of dilution is merely estimated. That is, the degree of dilution of the entire engine oil is gradually eliminated by increasing the temperature of the engine oil due to engine combustion heat or the like and evaporating the fuel contained in the engine oil as the temperature increases. Therefore, the degree of dilution cancellation, that is, the rate of decrease in the degree of dilution is calculated based on the temperature of the engine oil or a parameter having a correlation with the temperature. Such estimation may cause a situation that deviates from the actual state, and therefore may not be able to make an accurate determination.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to accurately determine the influence of dilution in determining abnormality of the fuel injection system based on the air-fuel ratio correction amount of air-fuel ratio feedback control. It is an object of the present invention to provide an abnormality diagnosis device for a direct injection internal combustion engine that can grasp and diagnose an abnormality.

  The abnormality diagnosis device according to the first invention diagnoses an abnormality of an internal combustion engine provided with a fuel injection means for injecting fuel into a cylinder. In this internal combustion engine, the lubricating oil diluted with the fuel injected by the fuel injection means is reduced to the intake system by the blow-by gas reduction device. This abnormality diagnosis device is provided in the exhaust system of the internal combustion engine, and performs feedback control so that the air-fuel ratio becomes the target air-fuel ratio based on the means for detecting the air-fuel ratio of the exhaust and the detected air-fuel ratio. An air-fuel ratio control means, and a judgment means for judging the abnormality of the fuel system by isolating the influence of blow-by gas based on the air-fuel ratio correction amount detected in at least two states where the operating state of the internal combustion engine is different. Including.

  According to the first invention, the lubricating oil may be diluted by the fuel injected into the cylinder (especially when cold), but the fuel contained in this lubricating oil is reduced to the intake system by the blow-by gas reduction device. The In such a case, the air-fuel mixture becomes rich, and the air-fuel ratio correction amount is greatly calculated by the air-fuel ratio control means. On the other hand, even if an injector abnormality that is an essential abnormality (for example, an abnormality that breaks the linear relationship between the fuel injection time and the fuel injection amount) occurs, the air-fuel ratio correction amount is greatly calculated by the air-fuel ratio control means. Is done. The determination means is detected in at least two states in which the operating state of the internal combustion engine is different (for example, when the pressure of the fuel supplied to the fuel injection means is high and low, before and after warming up the internal combustion engine, etc.) Based on the air-fuel ratio correction amount, the influence of blow-by gas is determined to determine whether the fuel system is abnormal. More specifically, if the air-fuel ratio does not fluctuate even if the fuel pressure is reduced, it can be determined that the fuel injection means is normal, and the air-fuel ratio correction amount is calculated largely from the diluted lubricating oil. It can be judged that the cause is that the generated blow-by gas has been processed, and it can be diagnosed that this is not an essential abnormality of the fuel system. On the contrary, if the fuel pressure is lowered, it can be determined that the fuel injection means is abnormal when the air-fuel ratio fluctuates, and the reason why the air-fuel ratio correction amount is largely calculated is that the blow-by gas generated from the diluted lubricating oil has been processed. It can be judged that the abnormality is not the cause but the abnormality of the fuel injection means, and it can be diagnosed as an essential abnormality of the fuel system. Furthermore, if the air-fuel ratio correction amount that was not large before warm-up becomes large after warm-up when fuel is evaporated from the diluted lubricating oil and processed as blow-by gas, the air-fuel ratio correction amount is calculated to be large. It can be judged that this is due to the treatment of blow-by gas generated from the diluted lubricating oil, and it can be diagnosed that this is not an essential abnormality of the fuel system. As a result, in determining the abnormality of the fuel injection system based on the air-fuel ratio correction amount of the air-fuel ratio feedback control, the influence of the dilution can be accurately grasped and the abnormality can be diagnosed. An abnormality diagnosis apparatus can be provided.

  In the abnormality diagnosis apparatus according to the second invention, in addition to the configuration of the first invention, the judging means includes means for judging an abnormality of the fuel system based on the difference in the air-fuel ratio correction amount.

  According to the second aspect of the invention, the air-fuel ratio correction amount is largely calculated based on the difference in the air-fuel ratio correction amount before and after the decrease in the fuel pressure and the difference in the air-fuel ratio correction amount before and after the warm-up of the internal combustion engine. It is possible to determine whether it is caused by an abnormality in the system or by treating blow-by gas generated from diluted lubricating oil.

  In the abnormality diagnosis device according to the third aspect of the invention, in addition to the configuration of the first aspect of the invention, the judging means judges the abnormality of the fuel system based on the difference in the air-fuel ratio correction amount before and after the fuel pressure is reduced. Means for doing so.

  According to the third invention, if the air-fuel ratio does not fluctuate even if the fuel pressure is lowered, it can be determined that the fuel injection means is normal. Therefore, it can be diagnosed that the large calculation of the air-fuel ratio correction amount is caused by processing the blow-by gas generated from the diluted lubricating oil, and it is not an essential abnormality of the fuel system. Conversely, if the fuel pressure is lowered and the air-fuel ratio fluctuates, it can be determined that the fuel injection means is abnormal. Therefore, it is determined that the reason why the air-fuel ratio correction amount is largely calculated is not caused by processing the blow-by gas generated from the diluted lubricating oil, but is caused by an abnormality in the fuel injection means. Can be diagnosed as abnormal.

  In the abnormality diagnosis device according to the fourth aspect of the invention, in addition to the configuration of the first aspect of the invention, the judging means judges the abnormality of the fuel system based on the difference in the air-fuel ratio correction amount before and after warming up the internal combustion engine. Means for.

  According to the fourth aspect of the present invention, when the temperature of the internal combustion engine rises after being warmed up, the fuel evaporates from the diluted lubricating oil and is processed as blow-by gas. If the air-fuel ratio correction amount that was not large before warm-up becomes large after warm-up, the large air-fuel ratio correction amount is calculated because the blow-by gas generated from the diluted lubricating oil is processed. Judging, it can be diagnosed as not an essential abnormality of the fuel system.

  An abnormality diagnosis device according to a fifth aspect of the present invention diagnoses an abnormality of an internal combustion engine provided with fuel injection means for injecting fuel into a cylinder. In this internal combustion engine, the lubricating oil diluted with the fuel injected by the fuel injection means is reduced to the intake system by the blow-by gas reduction device, and fuel cut is executed when a predetermined condition is satisfied. This abnormality diagnosis device is provided in the exhaust system of the internal combustion engine, and performs feedback control so that the air-fuel ratio becomes the target air-fuel ratio based on the means for detecting the air-fuel ratio of the exhaust and the detected air-fuel ratio. Air-fuel ratio control means, and determination means for determining an abnormality of the fuel system by isolating the influence of blow-by gas based on the air-fuel ratio in a state where the internal combustion engine is fuel cut.

  According to the fifth invention, since the blow-by gas is processed even during the fuel cut, if the fuel is evaporated from the diluted lubricating oil and processed as blow-by gas, it is detected when the fuel is not processed. Different air / fuel ratios. If fuel flows into the intake system as blow-by gas even during fuel cut, it is detected on the rich side even if fuel is not injected. When this is detected, it is determined that the large calculation of the air-fuel ratio correction amount is due to the processing of blow-by gas generated from the diluted lubricating oil. Can diagnose.

  In the abnormality diagnosis apparatus according to the sixth aspect of the invention, in addition to the configuration of the fifth aspect of the invention, the determination means is based on the output value from the air-fuel ratio sensor in a state where the internal combustion engine is fuel cut. Means for determining anomalies.

  According to the sixth aspect of the invention, the air-fuel ratio correction amount is largely calculated based on the rich-side air-fuel ratio detected when fuel flows into the intake system as blow-by gas even during fuel cut. It can be diagnosed that it is not an essential abnormality of the fuel system by judging that the cause is that the blow-by gas generated from the lubricating oil is processed.

  In addition to the configurations of the first to sixth inventions, the abnormality diagnosis apparatus according to the seventh invention further includes means for lighting the MIL in the OBD based on the result of the judging means.

  According to the seventh aspect of the present invention, it is possible to accurately turn on an OBD (On Board Diagnosis) MIL (Malfuction Indicator Lamp).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
FIG. 1 shows an overall configuration diagram of a direct injection engine controlled by the abnormality detection device according to the present embodiment.

  In the engine 10, a cylinder head 110 is covered above the cylinder block 100, and a piston 120 is slidably held in a cylinder 100A formed in the cylinder block 100. The reciprocating motion of the piston 120 in the cylinder 100A is converted into the rotational motion of the crankshaft 130 and transmitted to a transmission or the like. The crankshaft 130 is connected to the starter 30 via the flywheel 140 when the engine is started.

  A combustion chamber 1000 is formed above the piston 120 with the cylinder block 100 and the cylinder head 110 as chamber walls. In the combustion chamber 1000, a mixture of fuel and air is burned, and the piston 120 moves up and down by the explosive force. Move it. The air-fuel mixture is ignited by a spark plug 150 provided through the cylinder head 110 and protruding into the combustion chamber 1000.

  Supply of air constituting the air-fuel mixture is performed by an intake passage 1010 formed in the intake pipe connected to the cylinder head 110 and the cylinder head 110. Further, exhaust from the combustion chamber 1000 is performed by an exhaust passage 1020. The cylinder head 110 is provided with an intake valve 160 for switching communication between the intake passage 1010 and the combustion chamber 1000 and an exhaust valve 170 for switching communication between the exhaust passage 1020 and the combustion chamber 1000. ing.

  A flap-like throttle valve 190 is provided in the intake pipe, and the air flow in the intake passage 1010 is adjusted according to the opening.

  The fuel constituting the mixture is supplied by an electromagnetic in-cylinder injector 210. The in-cylinder injector 210 is provided to penetrate the cylinder head 110 and injects fuel into the combustion chamber 1000 from the tip nozzle portion.

  The fuel supplied to the in-cylinder injector 210 is supplied by boosting the fuel sucked from the fuel tank 250 in two stages by the low pressure pump 240 and the high pressure pump 230. The high-pressure pump 230 is driven by power transmitted from the crankshaft 130 of the engine 10 via a belt or the like. On the other hand, the low pressure pump 240 is driven electrically.

  Further, an engine control computer (hereinafter referred to as an engine ECU (Electronic Control Unit)) 60 that controls each part of the engine such as the spark plug 150, the throttle valve 190, the in-cylinder injector 210, and the like is provided. The engine ECU 60 has a general configuration including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like, and the ignition plug 150 is installed on the basis of detection signals from various sensors. Actuate, output a control signal to the throttle valve 190 to adjust the opening degree of the throttle valve 190 (throttle opening degree), energize the in-cylinder injector 210 by the control signal, and in the cylinder for a predetermined time at a predetermined timing The nozzle of the injector 210 for injection is opened.

  The engine ECU 60 includes an OBD. The OBD is a device that performs failure diagnosis using a diagnosis device mounted on the vehicle. In the present invention, when the OBD diagnoses an abnormality in the fuel system, the correction amount in the air-fuel ratio feedback control is monitored. When this correction amount increases excessively, it is determined to be abnormal. However, there is a case where the fuel component in the blow-by gas is increased after warm-up due to the dilution of the engine oil with the fuel that occurs in the cold state, and the air-fuel ratio is sometimes changed. Then, the engine ECU 60 processes. Actually, in such a case, MIL, which is an alarm lamp for notifying the driver of the occurrence of an abnormality, is not turned on without determining that the abnormality has occurred.

  A sensor that inputs a signal to the engine ECU 60 includes a mass flow meter 510 that measures the flow rate of air flowing through the intake passage 1010, a crank angle sensor 520, an A / F sensor 530, and a cooling that detects an engine cooling water temperature representative of the engine temperature. There are water temperature sensors. Further, when the driver operates the key at the time of start-up, an ignition (IG) on signal and a starter on signal are input to the engine ECU 60, and when the driver depresses the accelerator pedal 420, the amount of depression is input. It has become.

  The engine ECU 60 controls the combustion injection amount based on the intake air amount detected by the mass flow meter 510 or the like. At this time, the engine ECU 60 controls the injection amount and the injection timing according to the engine speed and the engine load so as to achieve an optimal combustion state based on signals from the sensors. In this engine 10, since fuel is directly injected into the cylinder, injection timing control and injection amount control are performed simultaneously. Further, the engine ECU 60 performs ignition timing control so as to achieve an optimal ignition timing based on signals (including a knocking sensor and the like) detected by the crank angle sensor 520, the cam position sensor, and the like. By such control, both high output and low emission of the engine 10 are realized. The engine ECU 60 operates the engine in a stoichiometric state throughout the normal operation region.

  Further, the engine ECU 60 performs air-fuel ratio feedback control so as to eliminate the deviation between the air-fuel ratio detected by the A / F sensor 530 and the target air-fuel ratio so that the air-fuel ratio of the exhaust becomes the target air-fuel ratio. . PI (or PID) control is used as the air-fuel ratio feedback control. The P component (proportional term, proportional gain) affects responsiveness, and the D component (integral term, integral gain) affects steady-state deviation.

  Further, the engine ECU 60 controls the pressure of fuel supplied to the in-cylinder injector 210 by controlling the high-pressure pump 230. At this time, for example, the high pressure pump 230 is controlled as follows to control the fuel pressure.

  The high-pressure pump 230 includes a pump plunger that reciprocates in the cylinder by the rotation of the cam, and a pressurizing chamber that includes the cylinder and the pump plunger. The pressurizing chamber includes a pump supply pipe that communicates with a feed pump that feeds fuel from the fuel tank, a return pipe that causes the fuel to flow out from the pressurizing chamber and return it to the fuel tank, and in-cylinder injector 210 High-pressure delivery pipes that are pumped toward are connected to each other. The high-pressure pump 230 is provided with an electromagnetic spill valve that opens and closes a pump supply pipe and a high-pressure delivery pipe and a pressurizing chamber.

  When the electromagnetic plunger spill valve is open and the pump plunger moves in the direction of increasing the volume of the pressurizing chamber, that is, when the high-pressure pump 230 is in the suction stroke, fuel is supplied from the pump supply pipe into the pressurizing chamber. Inhaled. Further, when the pump plunger moves in the direction in which the volume of the pressurizing chamber decreases, that is, when the high-pressure pump 230 is in the pumping stroke, if the electromagnetic spill valve is closed, the pump supply pipe, the return pipe, and the pressurizing chamber The gap is cut off, and the fuel in the pressurized chamber is pumped to the in-cylinder injector 210 via the high-pressure delivery pipe.

  In such a high-pressure pump 230, the fuel is pumped toward the in-cylinder injector 210 only during the closing period of the electromagnetic spill valve during the pumping stroke, and therefore, the closing timing of the electromagnetic spill valve is controlled. (By adjusting the closing period of the electromagnetic spill valve), the fuel pumping amount is adjusted. In other words, the fuel pumping amount increases by increasing the closing period by increasing the closing timing of the electromagnetic spill valve, and the fuel pumping amount by shortening the closing period by delaying the closing period of the electromagnetic spill valve. Less. When the fuel pumping amount increases, the fuel pressure in the high-pressure delivery pipe increases. When the fuel pumping amount decreases, the fuel pressure in the high-pressure delivery pipe decreases.

  In this way, the fuel delivered from the feed pump is pressurized by the high-pressure pump 230, and the pressurized fuel is pumped toward the in-cylinder injector 210 at an appropriate fuel pressure, so that the fuel directly into the combustion chamber. Even in an internal combustion engine that injects fuel, the fuel injection can be performed accurately.

  The engine 10 includes a blow-by gas reduction device (PCV (Positive Crankcase Ventilation) device). The blow-by gas is a mixed gas that leaks into the crankcase from the gap between the piston ring and the cylinder 100A, and the blow-by gas contains a large amount of hydrocarbons. Since it contains hydrocarbons, it is not good for the environment to release it to the atmosphere as it is, so blow-by gas is forcibly returned to the intake system through the PCV line using the negative pressure of the intake manifold. .

  The blow-by gas generated in the gap between the piston ring and the cylinder 100A passes through the cylinder head, is guided to the intake passage 1010 through the PCV pipe line. In this PCV pipe line, the negative pressure of the intake manifold acts, and blow-by gas is reduced downstream of the throttle valve 190 by the strength of the negative pressure.

  The lubrication system of the engine 10 includes an oil pan formed as a part of a crankcase and an engine oil supply device. The engine oil supply device includes an oil pump, a filter, an oil jet mechanism, and the like. Engine oil in the oil pan is sucked by the oil pump through the filter and supplied to the oil jet mechanism. In lubricating between the piston and the cylinder inner peripheral surface (bore), engine oil supplied to the oil jet mechanism is supplied from this mechanism to the cylinder inner peripheral surface. Thereafter, the engine oil is scraped downward from the inner circumferential surface of the cylinder as the piston reciprocates, and finally returned to the oil pan. The engine oil thus scraped off is mixed with the engine oil in the oil pan, and is then used for lubricating the engine 10 again. The engine oil supplied to the cylinder inner circumferential surface and used for lubricating the piston rises in temperature due to the combustion heat of the engine 10 and is then returned to the oil pan.

  The injector 210 is mounted so as to open directly into the combustion chamber of the engine 10 and injects fuel pressurized by the high-pressure pump 230 directly into the cylinder. When the engine 10 is cold, the atomization of fuel in the cylinder is difficult to promote, so that the fuel injected from the injector 210 causes the top surface of the piston 120 (piston top surface) and the cylinder inner peripheral surface (inside the cylinder). There is a tendency that a large amount adheres to the peripheral surface (bore). For this reason, normally, when cold, the fuel injection timing is set during the intake stroke (intake stroke injection), and the period from fuel injection to ignition is secured as long as possible to promote atomization of the injected fuel. I have to. However, even if such an intake stroke injection is performed, it is difficult to completely eliminate the fuel adhesion, and some fuels are not used for combustion and remain in the cylinders even after engine combustion. It will remain.

  Of this adhering fuel, the amount adhering to the inner peripheral surface of the cylinder is mixed with the engine oil adhering to the inner peripheral surface of the cylinder for lubricating the piston 120. As a result, engine oil is diluted with fuel. The engine oil in the cylinder diluted with the fuel is scraped off as the piston 120 moves up and down, returned to the oil pan, and used for lubricating the internal combustion engine. When the engine oil is diluted with such fuel (fuel is mixed in the lubricating oil) and the temperature of the engine oil rises, the fuel component contained in the engine oil becomes a gas, and is blown into the intake passage 1010 as a blow-by gas. Supplied.

  Thus, by diluting the engine oil with the fuel generated in the cold state, the fuel component in the blow-by gas is increased after warm-up, and the air-fuel ratio is changed. Since the PCV device itself cannot be stopped, whether the fluctuation of the air-fuel ratio is due to the processing of blow-by gas from oil diluted with such fuel, or is there an abnormality in the fuel system in the first place? It is difficult to isolate.

  With reference to FIG. 2, the relationship between the amount of intake air and the A / F deviation due to oil dilution of fuel will be described. As shown in FIG. 2, the A / F shift due to fuel oil dilution is larger as the load on the engine 10 is smaller because the PCV flow rate is constant, and smaller as the load on the engine 10 is larger. In the present invention, it is assumed that no A / F deviation occurs when all fuel system devices are normal and no oil dilution of the fuel has occurred.

  FIG. 3 shows the characteristics of the injector 210 (relationship between fuel injection time and fuel injection amount). When the fuel pressure is changed from a high state to a low state, when the injector 210 is normal, the fuel injection amount does not change (the fuel injection time changes), so the A / F does not change. on the other hand. When the injector 210 is abnormal, the fuel injection amount changes (the fuel injection time also changes), so the A / F changes.

  As described above, when the pressure of the fuel supplied to the injector 210 is changed (decreased), the A / F does not change if the injector 210 is normal, and the A / F changes if the injector 210 is abnormal. To do. By using this, in the present invention, the correction amount of the air-fuel ratio control is monitored, and when the air-fuel ratio correction amount increases excessively, when it is determined that an abnormality has occurred in the fuel injection system, Whether or not an abnormality has occurred in the fuel system (for example, an abnormality in the injector 210) or whether or not the fuel component obtained by diluting the oil simply enriched the air-fuel mixture as the temperature of the oil increases is determined.

  A control structure of a program executed by engine ECU 60 according to the present embodiment will be described with reference to FIG. This program is one subroutine program among the programs executed by the engine ECU 60, and is repeatedly executed every predetermined cycle time.

  In step (hereinafter, step is abbreviated as S) 100, engine ECU 60 monitors fuel system OBD. In particular, the air-fuel ratio correction amount (hereinafter sometimes referred to as A / F correction amount) is monitored in a state where air-fuel ratio control is being performed. In S110, engine ECU 60 determines whether or not the A / F correction amount is equal to or greater than a threshold value. This threshold value is set as an excessive value such that an abnormality is recognized in the air-fuel ratio control. If the A / F correction amount is equal to or greater than the threshold value (YES in S110), the process proceeds to S120. Otherwise (NO in S110), this process ends.

  In S120, engine ECU 60 detects the A / F correction amount at this time and stores it as A / F correction amount (1) (A / F correction amount before fuel pressure reduction). In S130, engine ECU 60 delays the closing start timing of the electromagnetic spill valve of high pressure pump 230, shortens the valve closing period, and lowers the fuel pressure. Since the valve closing period is shortened, the fuel pumping amount is reduced, and the pressure of the fuel in the high pressure delivery pipe is lowered. In S140, engine ECU 60 detects the A / F correction amount at this time, and stores it as A / F correction amount (2) (A / F correction amount after the fuel pressure is lowered).

  In S150, engine ECU 60 calculates the A / F correction amount difference as | A / F correction amount (1) −A / F correction amount (2) |. In S160, engine ECU 60 determines whether or not the correction amount difference is greater than or equal to the injector abnormality determination threshold value. If the correction amount difference is greater than or equal to the injector abnormality determination threshold value (YES in S160), the process proceeds to S170. If not (NO in S160), the process proceeds to S180.

  In S170, engine ECU 60 determines that injector 210 is abnormal, and turns on MIL (fuel system abnormality). In S180, engine ECU 60 determines that injector 210 is normal, turns on dilution determination (flag), and suspends lighting of MIL (abnormal fuel system).

  An abnormality diagnosis operation when the engine controlled by engine ECU 60 according to the present embodiment is performing air-fuel ratio control based on the above-described structure and flowchart will be described.

  The engine 10 is started and the fuel system OBD is monitored (S100). More specifically, the A / F correction amount that is the correction amount of the air-fuel ratio feedback control is the monitoring target. If the A / F correction amount is equal to or greater than the threshold value (YES in S110), the A / F correction amount (1) before the fuel pressure is reduced is detected (S120). Next, the pressure (fuel pressure) of the fuel supplied to the injector 210 is reduced (S130), and the A / F correction amount (2) after the fuel pressure is reduced is detected (S140).

  A difference in the A / F correction amount before and after the fuel pressure is reduced is calculated, and if this correction amount difference is equal to or greater than the injector abnormality determination threshold value (YES in S160), the injector 210 is abnormal. As a result of OBD diagnosis, the MIL is turned on (fuel system abnormality). On the other hand, if the correction amount difference is not equal to or greater than the injector abnormality determination threshold value (NO in S160), injector 210 is not abnormal, and oil dilution occurs with fuel when cold, and the fuel evaporates from the oil after warm-up. Then, it is determined that the A / F correction amount is increased by being supplied to the intake passage 1010 as blow-by gas. In this case, the injector 210 is normal, the dilution determination flag is turned on, and the lighting of the fuel system abnormality MIL is suspended.

  As described above, according to the abnormality detection device of the present embodiment, in the air-fuel ratio feedback control, if the correction amount becomes excessively large, it is diagnosed that an abnormality has occurred in the fuel system. In this case, once the fuel pressure of the high-pressure fuel system is reduced and the air-fuel ratio does not change, it is determined that the injector is normal, and the blow-by gas generated from the oil diluted with the fuel is changed. It is determined that it has been processed, and the lighting of the MIL is reserved. On the other hand, if the fuel pressure of the high-pressure fuel system is reduced and the air-fuel ratio fluctuates, it is determined that an abnormality has occurred in the fuel system including the injector, and the MIL is turned on. Since the separation process performed by once decreasing the fuel pressure of the high-pressure fuel system is performed only when the correction amount of the air-fuel ratio feedback control becomes excessively large, the deterioration of drivability does not become remarkable.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described. Note that the same structure (including hardware and flowcharts) as that of the first embodiment will not be described repeatedly.

  Engine 10 controlled by engine ECU 60 according to the present embodiment includes an engine cooling water temperature sensor that detects the temperature of engine cooling water in addition to the overall configuration diagram of FIG. Engine ECU 60 executes a program shown in a flowchart different from the flowchart shown in FIG.

  With reference to FIG. 5, a control structure of a program executed by engine ECU 60 according to the present embodiment will be described. In the flowchart shown in FIG. 5, the same steps as those in the flowchart shown in FIG. Their processing is the same. Therefore, detailed description thereof will not be repeated here.

  In S200, engine ECU 60 detects the A / F correction amount before engine 10 is warmed up (when cold) and stores it as A / F correction amount (3).

  In S210, engine ECU 60 determines whether or not the engine cooling water temperature is equal to or higher than the warm-up completion water temperature. The engine coolant temperature is detected based on a signal from the engine coolant temperature sensor. If the engine cooling water temperature is equal to or higher than the warm-up completion water temperature (YES in S210), the process proceeds to S220. If not (NO in S210), the process returns to S210 and waits until the engine cooling water temperature becomes equal to or higher than the warm-up completion water temperature.

  In S220, engine ECU 60 detects the A / F correction amount after warm-up of engine 10 as the A / F correction amount (4). In S230, engine ECU 60 calculates the A / F correction amount difference as | A / F correction amount (3) −A / F correction amount (4) |. In S240, engine ECU 60 determines whether or not the correction amount difference is greater than or equal to the dilution occurrence determination threshold value. If the correction amount difference is equal to or greater than the dilution occurrence determination threshold value (YES in S240), the process proceeds to S260. If not (NO in S240), the process proceeds to S250.

  In S250, engine ECU 60 turns off dilution determination (flag) because the A / F abnormality is not caused by oil dilution with fuel, and if the other abnormality of the fuel system (for example, injector 210 abnormality) can be specified, MIL is determined. Turn on (fuel system abnormality). In S260, engine ECU 60 turns on dilution determination (flag) and suspends lighting of MIL (fuel system abnormality) because the A / F abnormality is caused by oil dilution with fuel.

  An abnormality diagnosis operation when the engine controlled by engine ECU 60 according to the present embodiment is performing air-fuel ratio control based on the above-described structure and flowchart will be described.

  The engine 10 is started and the A / F correction amount when the engine is cold before being warmed up is detected and stored as the A / F correction amount (3) (S200). This A / F correction amount (3) is in a state where there is no influence as blow-by gas because the fuel contained in the oil does not evaporate because it is at a low temperature.

  When the fuel system OBD is monitored (S100) and the A / F correction amount becomes equal to or greater than the threshold value (YES in S110), the engine 10 waits for the warm-up of the engine 10 to complete (YES in S210). The F correction amount (4) is detected (S220).

  When the difference between the A / F correction amounts before and after warm-up is calculated and this correction amount difference is equal to or greater than the dilution occurrence determination threshold value (YES in S240), oil dilution with fuel occurs during cold weather. It is determined that the A / F correction amount has increased because the fuel has evaporated from the oil after warming up and supplied to the intake passage 1010 as blow-by gas (S260). In this case, the injector 210 is normal, the dilution determination flag is turned on, and the lighting of the fuel system abnormality MIL is suspended. On the other hand, if this correction amount difference is not equal to or greater than the dilution occurrence determination threshold value (NO in S240), it is an abnormality of injector 210, etc., so that MIL (fuel system abnormality) is turned on as a diagnosis result of fuel system OBD ( S250).

As described above, according to the abnormality detection device of the present embodiment, in the air-fuel ratio feedback control, if the correction amount becomes excessively large, it is diagnosed that an abnormality has occurred in the fuel system. In this case, if the difference between the cold air-fuel ratio correction amount and the warm-up air-fuel ratio correction amount is large, the air-fuel ratio is generated because blow-by gas is generated from the oil diluted with the fuel due to the high temperature. Is turned on, and the lighting of the MIL is reserved. By monitoring the air-fuel ratio correction amount, when the correction amount is excessively large, it is possible to determine whether it is simply the effect of oil dilution with fuel or the abnormality of the fuel system <Third Embodiment>
Hereinafter, a third embodiment of the present invention will be described. Note that the same structure (including hardware and flowcharts) as that of the first embodiment will not be described repeatedly.

  In engine 10 controlled by engine ECU 60 according to the present embodiment, A / F sensor 530 in the overall configuration diagram of FIG. 1 outputs current value IL monitored by OBD to engine ECU 60. The current value IL measures the atmosphere flowing through the intake passage 1010 during the fuel cut. If blow-by gas is reduced by the PCV device even during fuel cut, the IL value becomes smaller than this predetermined threshold value. Engine ECU 60 executes a program shown in a flowchart different from the flowchart shown in FIG.

  A control structure of a program executed by engine ECU 60 according to the present embodiment will be described with reference to FIG. In the flowchart shown in FIG. 6, the same steps as those in the flowchart shown in FIG. 4 or 5 are given the same step numbers. Their processing is the same. Therefore, detailed description thereof will not be repeated here.

  In S300, engine ECU 60 determines whether engine 10 is in a fuel cut or not. If engine 10 is being fuel cut (YES in S300), the process proceeds to S310. If not (NO in S300), the process returns to S300 and waits until fuel cut is started.

  The fuel cut control is a control for stopping the supply of fuel during deceleration in order to improve the fuel efficiency of the vehicle. This fuel cut control is a control that improves fuel efficiency by reducing the supply of fuel to the engine 10 as much as possible within a range that does not impair running performance and riding comfort. In general, the supply of fuel is stopped when the rotational speed of the engine 10 enters a predetermined range (deceleration of the fuel cut speed or higher) during deceleration while the engine 10 is idling. Specifically, the fuel supply is stopped when the throttle valve 190 is closed during traveling and the rotational speed of the engine 10 is equal to or higher than the fuel cut rotational speed. Further, when the rotational speed of the engine 10 decreases and reaches the return rotational speed (fuel cut return rotational speed) that defines the lower limit of the range, the fuel supply is resumed.

  In S310, engine ECU 60 detects an IL value that is a current value of A / F sensor 530 during the fuel cut. In S320, engine ECU 60 determines whether or not the IL value is greater than or equal to the dilution occurrence determination threshold value. If the IL value is greater than or equal to the dilution occurrence determination threshold value (YES in S320), the process proceeds to S260. If not (NO in S320), the process proceeds to S250.

  An abnormality diagnosis operation when the engine controlled by engine ECU 60 according to the present embodiment is performing air-fuel ratio control based on the above-described structure and flowchart will be described.

  The engine 10 is started, the fuel system OBD is monitored (S100), and if the A / F correction amount is equal to or greater than the threshold value (YES in S110), it waits for the fuel cut of the engine 10 to start (S300). And YES), the IL value of the A / F sensor 530 is detected (S310).

  If the IL value, which is the output current value of A / F sensor 530 during fuel cut, is equal to or greater than the dilution occurrence determination threshold value (YES in S320), oil dilution with fuel occurs in the cold state and after warming up It is determined that the A / F correction amount has increased due to the fuel evaporating from the oil and supplied to the intake passage 1010 as blow-by gas (S260). In this case, the injector 210 is normal, the dilution determination flag is turned on, and the lighting of the fuel system abnormality MIL is suspended. On the other hand, if this correction amount difference is not equal to or greater than the dilution occurrence determination threshold value (NO in S320), it is an abnormality of injector 210 and so on, and MIL (fuel system abnormality) is turned on as a diagnosis result of fuel system OBD ( S250).

As described above, according to the abnormality detection device of the present embodiment, in the air-fuel ratio feedback control, if the correction amount becomes excessively large, it is diagnosed that an abnormality has occurred in the fuel system. In this case, if the output value of the A / F sensor during the fuel cut is detected and the IL value that is the value is equal to or less than the threshold value, the blow-by gas is generated from the oil diluted with the fuel, so the air-fuel ratio Is turned on, and the lighting of the MIL is reserved. By monitoring the air-fuel ratio correction amount, when the correction amount is excessively large, it is possible to determine whether it is simply the effect of oil dilution with fuel or the abnormality of the fuel system. Note that the above-described first embodiment The processing of S120 to S160 (injector abnormality determination processing) can also be applied to the second embodiment and the third embodiment. In this way, the abnormality of the injector can be determined more accurately.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is an overall configuration diagram of an engine controlled by an engine control device according to a first embodiment of the present invention. It is a figure which shows the relationship between the amount of intake air, and A / F deviation by the oil dilution of fuel. It is a figure which shows the characteristic (relationship of fuel injection time and fuel injection amount) of an injector. It is a flowchart which shows the control structure of the program performed by engine ECU which is an engine control apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the control structure of the program performed by engine ECU which is an engine control apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the control structure of the program performed by engine ECU which is an engine control apparatus which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

  10 engine, 30 starter, 60 engine ECU, 150 spark plug, 160 intake valve, 170 exhaust valve, 190 throttle valve, 210 injector, 520 crank angle sensor, 1000 combustion chamber, 1010 intake passage, 1020 exhaust passage.

Claims (7)

An abnormality diagnosis device for an internal combustion engine comprising fuel injection means for injecting fuel into a cylinder,
In the internal combustion engine, the lubricating oil diluted with the fuel injected by the fuel injection means is reduced to the intake system by the blow-by gas reduction device,
The abnormality diagnosis device includes:
Means provided in the exhaust system of the internal combustion engine for detecting the air-fuel ratio of the exhaust;
Air-fuel ratio control means for performing feedback control based on the detected air-fuel ratio so that the air-fuel ratio becomes a target air-fuel ratio;
In-cylinder injection including a determination unit for determining an abnormality in the fuel system by isolating the influence of the blow-by gas based on air-fuel ratio correction amounts detected in at least two states in which the operating state of the internal combustion engine is different Abnormality diagnosis device for an internal combustion engine.   The abnormality diagnosis apparatus for a direct injection internal combustion engine according to claim 1, wherein the determination means includes means for determining an abnormality in the fuel system based on the difference in the air-fuel ratio correction amount.   The in-cylinder injection internal combustion engine according to claim 1, wherein the determination means includes means for determining an abnormality in the fuel system based on a difference in the air-fuel ratio correction amount before and after the fuel pressure is decreased. Abnormality diagnosis device.   The in-cylinder injection internal combustion engine according to claim 1, wherein the determination means includes means for determining an abnormality in the fuel system based on a difference in the air-fuel ratio correction amount before and after warming up the internal combustion engine. Abnormality diagnosis device. An abnormality diagnosis device for an internal combustion engine comprising fuel injection means for injecting fuel into a cylinder,
In the internal combustion engine, the lubricating oil diluted with the fuel injected by the fuel injection means is reduced to the intake system by the blow-by gas reduction device, and a fuel cut is executed when a predetermined condition is satisfied,
The abnormality diagnosis device includes:
Means provided in the exhaust system of the internal combustion engine for detecting the air-fuel ratio of the exhaust;
Air-fuel ratio control means for performing feedback control based on the detected air-fuel ratio so that the air-fuel ratio becomes a target air-fuel ratio;
An abnormality diagnosis for a cylinder injection type internal combustion engine, comprising: determination means for determining an abnormality of a fuel system by isolating an influence of the blow-by gas based on an air-fuel ratio in a state where the internal combustion engine is fuel cut. apparatus.   6. The in-cylinder injection type according to claim 5, wherein the determining means includes means for determining an abnormality in the fuel system based on an output value from an air-fuel ratio sensor in a state where the internal combustion engine is fuel cut. Abnormality diagnosis device for internal combustion engine.   The abnormality diagnosis apparatus for a direct injection internal combustion engine according to any one of claims 1 to 6, wherein the abnormality diagnosis apparatus further includes means for lighting a MIL in the OBD based on a result of the determination means.

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