Abnormality diagnostic device for internal combustion engine

Abstract

To provide an abnormality diagnostic device for an internal combustion engine capable of determining an abnormality of increase in blow-by gas caused by a piston ring stick.SOLUTION: An abnormality diagnostic device for an internal combustion engine includes: a detection section that detects whether or not exhaust gas recirculation functions; a measurement section that measures a suction air amount introduced into a combustion chamber; and a determination section that determines an abnormality of increase in blow-by gas on the basis of the fact that the measured suction air amount is lower than a normal time suction air amount calculated from engine speed and load when the exhaust gas recirculation does not function and the measured suction air amount is a predetermined value or larger.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a device for diagnosing abnormalities in an internal combustion engine mounted on a vehicle. [Background technology]

[0002] Patent Document 1 discloses an abnormality diagnosis device for an internal combustion engine that can detect when a blow-by gas passage has become disconnected from the intake passage and when the blow-by gas passage is damaged. This internal combustion engine abnormality diagnosis device describes that, when the PCV pressure sensor value is lower than atmospheric pressure when the amount of change in intake air volume is equal to or greater than a predetermined value, it determines that an abnormality has occurred on the intake passage side of the PCV pressure sensor based on the difference between the PCV pressure sensor value and atmospheric pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-186702 Summary of the Invention [Problem to be solved by the invention]

[0004] The abnormality diagnosis device for an internal combustion engine described in Patent Document 1 can determine abnormalities caused by disconnection or clogging of the blow-by gas passage from the PCV pressure sensor value, but has the problem of being unable to determine abnormalities such as an increase in blow-by gas caused by piston ring stick inside the engine.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an abnormality diagnosis device for an internal combustion engine that can determine an abnormality in an increase in blow-by gas due to piston ring stick. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the disclosed technology is an abnormality diagnosis device for an internal combustion engine, which includes a judgment unit that determines whether exhaust gas recirculation is enabled or not, a measurement unit that measures the amount of intake air introduced into the combustion chamber, and a judgment unit that, when exhaust gas recirculation is not enabled and the measured amount of intake air is equal to or greater than a predetermined value, determines that an abnormality of increased blow-by gas exists based on the fact that the measured amount of intake air is lower than the normal intake air amount calculated from the engine speed and load. [Effects of the Invention]

[0007] According to the abnormality diagnosis device for an internal combustion engine of the present disclosure, it is possible to determine an abnormality in an increase in blow-by gas due to piston ring stick. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating an abnormality diagnosis device and an internal combustion engine according to an embodiment of the present disclosure; FIG. [Figure 2A] Process flowchart of abnormality diagnosis of an internal combustion engine executed by an abnormality diagnosis device [Figure 2B] Process flowchart of abnormality diagnosis of an internal combustion engine executed by an abnormality diagnosis device DETAILED DESCRIPTION OF THE INVENTION

[0009] <Embodiment> [composition] 1 is a diagram showing a schematic functional block diagram of an abnormality diagnosis device 100 according to an embodiment of the present disclosure and a schematic configuration of an internal combustion engine 200 to be diagnosed. The internal combustion engine 200 is, for example, an engine mounted on a vehicle or the like.

[0010] The internal combustion engine 200 shown in Fig. 1 is an internal combustion engine equipped with exhaust gas recirculation (EGR), not shown. A crankcase is provided at the bottom of a cylinder block 280 of the internal combustion engine 200, and a crankshaft 283 connected to a piston 281 via a connecting rod 282 is housed inside the crankcase. An oil pan 290 is attached to the bottom of the cylinder block 280, and the oil pan 290 stores oil that circulates within the internal combustion engine 200. Furthermore, a cylinder head 270 is attached to the top of the cylinder block 280, and a cylinder head cover 260 is attached to the top of this cylinder head 270.

[0011] A plurality of cylinders are defined by a cylinder block 280 and a cylinder head 270. Only one cylinder is shown in Fig. 1. A piston 281 is housed in each cylinder, and the piston 281 reciprocates within the cylinder, causing a crankshaft 283 to rotate.

[0012] An intake passage (intake manifold) 241 and an exhaust passage 242 are connected to the cylinder head 270. Intake air flowing through the intake passage 241 is introduced into a combustion chamber 243, mixed with fuel, and combusted in the combustion chamber 243. Exhaust gas generated in the combustion chamber 243 by the combustion of the air-fuel mixture is discharged to the exhaust passage 242. A throttle valve 250 is provided upstream of the intake passage 241, and an air cleaner 210 is connected upstream of the throttle valve 250 via an intake passage (air inlet duct) 230. The air cleaner 210 is provided with an air flow meter 220 that detects an intake air amount Ga, which is the amount of intake air flowing through the intake passage 230, and outputs a signal corresponding to the intake air amount Ga as a detection signal.

[0013] The internal combustion engine 200 has a path that returns blow-by gas (unburned gas) that has leaked from the combustion chamber 243 into the crankcase to the intake passage 241. This blow-by gas return path is made up of a ventilation case 300 provided in the cylinder block 280, a communication passage 310 formed across the cylinder block 280 and the cylinder head 270, a PCV valve 320, and a blow-by gas passage 330. This blow-by gas return path is provided with a PCV pressure sensor (not shown) that detects the absolute pressure in the blow-by gas passage 330.

[0014] Furthermore, the internal combustion engine 200 is provided with a passage (not shown) that connects the cylinder block 280 and the cylinder head cover 260, and blow-by gas also leaks into the space formed by the cylinder head 270 and the cylinder head cover 260. This blow-by gas is returned to the intake passage 230 through a ventilation hose 340 that connects the cylinder head cover 260 and the intake passage 230.

[0015] The abnormality diagnosis device 100 is configured to diagnose whether or not an abnormality has occurred in the internal combustion engine 200. Typical abnormalities diagnosed by the abnormality diagnosis device 100 include abnormalities due to disconnection or clogging of the blow-by gas return path. Furthermore, the abnormality diagnosis device 100 of this embodiment determines an abnormality of increased blow-by gas due to piston ring stick, in which carbon or sludge generated in the combustion chamber 243 hardens and prevents the piston 281 from moving smoothly. This abnormality diagnosis device 100 includes an EGR determination unit 110, a Ga measurement unit 120, and an abnormality determination unit 130.

[0016] The EGR determination unit 110 determines whether or not a so-called exhaust gas recirculation (EGR) function is operating, which returns exhaust gas once discharged by combustion back into the intake path and sends it to the combustion chamber 243. The Ga measurement unit 120 measures the amount of intake air Ga introduced into the combustion chamber 243. The abnormality determination unit 130 determines, under specific conditions, an abnormality in the increase in blow-by gas in the internal combustion engine 200. The processing performed by these components will be described below.

[0017] [control] Next, control performed by the abnormality diagnosis device 100 according to an embodiment of the present disclosure will be described with further reference to Figures 2A and 2B. Figures 2A and 2B are flowcharts illustrating the procedure of abnormality diagnosis processing for the internal combustion engine 200, which is executed by each component of the abnormality diagnosis device 100. The processing in Figure 2A and the processing in Figure 2B are connected by a connector X.

[0018] (Step S11) The EGR determination unit 110 determines whether the exhaust gas recirculation (EGR) function is operating (whether EGR is on). When EGR is on, factors that cause variations in the intake air amount Ga increase due to variations in the EGR gas flow rate and EGR gas temperature. Therefore, this determination is made to eliminate errors due to the influence of EGR gas. If the EGR determination unit 110 determines that the EGR is on (step S11, Yes), the process ends without performing an abnormality diagnosis of the internal combustion engine 200. On the other hand, if the EGR determination unit 110 determines that the EGR is not on (step S11, No), the process proceeds to step S12.

[0019] (Step S12) The Ga measurement unit 120 measures the amount of intake air Ga introduced into the combustion chamber 243. This measurement is performed by obtaining, from the air flow meter 220, a detection signal corresponding to the amount of intake air Ga detected by the air flow meter 220. When the intake air amount Ga is measured by the Ga measurement unit 120, the process proceeds to step S13.

[0020] (Step S13) The abnormality determination unit 130 determines whether the intake air amount Ga measured by the Ga measurement unit 120 (hereinafter referred to as "measured Ga") is greater than a predetermined value. This determination is made to eliminate the small Ga condition and improve the determination accuracy, since the determination accuracy decreases when the intake air amount Ga is small. Therefore, the predetermined value can be set to a value that can be expected to provide a certain degree of determination accuracy (for example, a value that is 80% of the maximum intake air amount Ga). If the abnormality determination unit 130 determines that the measured Ga is greater than the predetermined value (step S13, Yes), the process proceeds to step S14. On the other hand, if the abnormality determination unit 130 determines that the measured Ga is equal to or less than the predetermined value (step S13, No), the process ends without performing an abnormality diagnosis of the internal combustion engine 200.

[0021] (Step S14) The abnormality determination unit 130 determines whether the Ga measured by the Ga measurement unit 120 is less than a predetermined intake air amount Ga under normal conditions (hereinafter referred to as "normal Ga"). This normal Ga is an intake air amount Ga calculated by a known method from the engine speed and load (KL), and is given as a Ga map under operating conditions, for example. An example of this determination is whether the measured Ga is smaller than a value (for example, XX%) extracted from the Ga map. If the abnormality determination unit 130 determines that the measured Ga is less than the normal Ga (step S14, Yes), the process proceeds to step S15. On the other hand, if the abnormality determination unit 130 determines that the measured Ga is equal to or greater than the normal Ga (step S14, No), the process proceeds to step S16.

[0022] (Step S15) The abnormality determination unit 130 determines the count value C of the Ga abnormality counter. ga is incremented by 1. This Ga abnormality counter is a counter that counts the number of times that it is determined in step S14 that the measured Ga has fallen below the normal Ga. The abnormality determination unit 130 determines the count value C of the Ga abnormality counter. ga When the count is incremented by one, the process proceeds to step S17.

[0023] (Step S16) The abnormality determination unit 130 determines the count value C of the Ga abnormality counter. ga is cleared, and the process ends without performing an abnormality diagnosis on the internal combustion engine 200.

[0024] (Step S17) The abnormality determination unit 130 determines the count value C of the Ga abnormality counter. ga It is determined whether or not the intake air amount Ga has exceeded a predetermined value N. This value N is set in order to accurately determine whether a decrease in the intake air amount Ga has occurred. The abnormality determination unit 130 determines the count value C of the Ga abnormality counter. ga If it is determined that the count value C of the Ga abnormality counter exceeds the N value (YES in step S17), the process proceeds to step S18. ga If it is determined that does not exceed the N value (step S17, No), the process proceeds to step S11.

[0025] (Step S18) The system checks for intake leaks and clogged air cleaner 210. To check for intake leaks, a check is made to see if air is being sucked in due to a loose clamp between air flow meter 220 and throttle valve 250. To check for clogged air cleaner 210, a check is made to see if there is an increase in passage resistance due to dirt on the air cleaner element. The results of these checks are reflected in abnormality determination unit 130. If the intake air leak and the clogging of the air cleaner 210 are checked, the process proceeds to step S19.

[0026] (Step S19) The abnormality determination unit 130 determines whether there is an intake air leak or a clog in the air cleaner 210. This determination is made to determine whether the decrease in the intake air amount Ga is due to a measurement error. If the abnormality determination unit 130 determines that there is no intake air leak or clogging of the air cleaner 210 (step S19, NO), the process proceeds to step S20. On the other hand, if the abnormality determination unit 130 determines that there is an intake air leak or clogging of the air cleaner 210 (step S19, YES), the process proceeds to step S21.

[0027] (Step S20) The abnormality determination unit 130 determines that an engine abnormality has occurred when there is no intake air leak or clogging of the air cleaner 210, the intake air amount Ga is measured normally, and a decrease in the intake air amount Ga has occurred. If it determines that the engine is abnormal, it can issue an alarm by setting an engine abnormality flag. When the abnormality determination unit 130 determines that an engine abnormality has occurred, the abnormality diagnosis of the internal combustion engine 200 ends.

[0028] (Step S21) Any necessary repairs, such as replacement or cleaning, will be made to eliminate intake leaks and clogged air cleaner 210. When the intake air leak and / or the blockage of the air cleaner 210 is resolved, this state is reflected in the abnormality determination unit 130, and the process proceeds to step S22.

[0029] (Step S22) The abnormality determination unit 130 determines the count value C of the Ga abnormality counter. ga is cleared, and the process ends without performing an abnormality diagnosis on the internal combustion engine 200.

[0030] When an engine abnormality occurs due to a stuck piston ring or the like, a decrease in the intake air amount Ga is observed before the crankcase pressure rises during steady engine operation. This decrease in the intake air amount Ga is caused by the fact that blow-by gas begins to increase when the piston ring sticks, and as a result, the increase in blow-by gas after the airflow makes it difficult for the intake air amount Ga to flow. For this reason, by detecting the decrease in the intake air amount Ga, it is possible to detect an abnormality before the blow-by gas (crankcase pressure) suddenly increases due to a stuck piston ring or the like.

[0031] <Actions and Effects> As described above, according to the internal combustion engine abnormality diagnosis device according to one embodiment of the present disclosure, when exhaust gas recirculation (EGR) is not on and the measured intake air amount (measured Ga) is equal to or greater than a predetermined value, it confirms that there are no intake leaks or clogged air cleaner, and then determines an engine abnormality due to increased blow-by gas based on the fact that the measured Ga remains lower than the normal intake air amount (normal Ga) calculated from the engine speed and load for a predetermined number of times (N value) or more.

[0032] This makes it possible to determine the abnormality of increased blow-by gas caused by piston ring stick while eliminating the effects of EGR variation, low accuracy judgment at small flow rates, intake leaks, and air cleaner blockages.

[0033] <Application example> An engine abnormality may be determined by detecting the intake air amount Ga and the intake manifold internal pressure (PIM). Even if the intake air amount Ga decreases, the decrease is replaced by an increase in blow-by gas, so the flow rate at the measurement section that measures the intake manifold internal pressure does not change. For this reason, it is possible to determine an engine abnormality by determining that there is no decrease in the intake manifold internal pressure instead of checking for intake leaks. [Industrial Applicability]

[0034] The internal combustion engine abnormality diagnosis device of the present disclosure can be used when it is desired to determine whether there is an abnormality in the increase in blow-by gas due to piston ring stick. [Explanation of symbols]

[0035] 100 Abnormality diagnosis device 110 EGR judgment section 120 Ga measurement unit 130 Abnormality determination section 200 Internal combustion engine 210 Air Cleaner 220 Air Flow Meter 230 Intake passage (air inlet duct) 241 Intake passage (intake manifold) 242 Exhaust passage 243 Combustion Chamber 250 Throttle valve 260 Cylinder head cover 270 cylinder head 280 cylinder block 281 Piston 282 Connecting rod 283 Crankshaft 290 Oil pan 300 Ventilation Case 310 Communication path 320 PCV valve 330 Blow-by gas passage 340 Ventilation Hose

Claims

[Claim 1] An abnormality diagnosis device for an internal combustion engine, a determination unit for determining whether exhaust gas recirculation is on; a measuring unit for measuring the amount of intake air introduced into the combustion chamber; and a determination unit that, when the exhaust gas recirculation is not turned on and the measured intake air amount is equal to or greater than a predetermined value, determines that an abnormality of an increase in blow-by gas exists based on the fact that the measured intake air amount is lower than a normal intake air amount calculated from the engine speed and load. An abnormality diagnosis device for internal combustion engines.

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