JP2019183674A - Internal combustion engine diagnostic system - Google Patents

Abstract

To detect a caulking failure of a compressor due to oil mixed with a blow-by gas and returned to an intake passage.SOLUTION: An internal combustion engine 1 includes: a compressor 14C of a turbocharger 14 installed in an intake passage 3; and a blow-by gas passage 25 connected to the intake passage at a position upstream of the compressor. A diagnostic system 100 is configured to determine whether a caulking failure occurs in the compressor based on an operation time of the internal combustion engine or the correlation value thereof and compressor efficiency of the compressor.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a diagnostic apparatus for an internal combustion engine, and more particularly to a diagnostic apparatus for diagnosing whether or not a coking abnormality has occurred in a compressor of a turbocharger.

  A blow-by gas recirculation device for recirculating blow-by gas leaked into a crankcase from a gap between a piston and a cylinder to an intake passage is known. A turbocharged internal combustion engine provided with a turbocharger compressor in an intake passage is also known.

Japanese Patent Laying-Open No. 2015-108333

  A blow-by gas passage for circulating the blow-by gas may be connected to a position upstream of the compressor in the intake passage. In this case, the oil mixed in the blow-by gas is also circulated through the intake passage, and the coking abnormality may occur in the compressor due to the oil.

  Accordingly, the present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a diagnostic device for an internal combustion engine that can detect a coking abnormality of a compressor caused by oil mixed in blow-by gas and circulated in an intake passage. There is to do.

According to one aspect of the present disclosure,
A diagnostic device for an internal combustion engine,
The internal combustion engine
A turbocharger compressor installed in the intake passage;
A blow-by gas passage connected to the intake passage at a position upstream of the compressor;
With
The diagnostic apparatus is configured to determine whether or not a coking abnormality has occurred in the compressor based on an operation time of the internal combustion engine or a correlation value thereof and a compressor efficiency of the compressor. An internal combustion engine diagnostic apparatus is provided.

  Preferably, the diagnostic device stores in advance a relationship between an operating time of the internal combustion engine or a correlation value thereof and the compressor efficiency, and determines whether or not the coking abnormality has occurred using the relationship.

  Preferably, the diagnostic device acquires the compressor efficiency corresponding to the actual operation time or the correlation value from the relationship, calculates the actual compressor efficiency, and calculates the compressor efficiency acquired from the relationship and the calculated actual A difference with the compressor efficiency is calculated, and the difference is compared with a predetermined threshold value to determine whether or not the coking abnormality has occurred.

  Preferably, the diagnostic device calculates the actual compressor efficiency based on a compressor inlet temperature, a compressor outlet temperature, a compressor inlet pressure, a compressor outlet pressure, and an atmospheric pressure.

  Preferably, the internal combustion engine is mounted on a vehicle, and the diagnostic device determines whether the coking abnormality has occurred based on a travel distance of the vehicle, which is a correlation value of an operation time of the internal combustion engine, and the compressor efficiency. Determine whether.

  According to the present disclosure, it is possible to detect a compressor coking abnormality caused by oil mixed in blow-by gas and circulated in the intake passage.

It is the schematic which shows the structure of embodiment. The map which defined the relationship between mileage and compressor efficiency is shown. It is a flowchart of the routine of a diagnostic process.

  Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that the present disclosure is not limited to the following embodiments.

  FIG. 1 is a schematic diagram illustrating a configuration of an embodiment of the present disclosure. The internal combustion engine (engine) 1 is a multi-cylinder compression ignition internal combustion engine, that is, a diesel engine mounted on a vehicle (not shown). The vehicle is a large vehicle such as a truck. However, there are no particular limitations on the types, types, applications, and the like of the vehicle and the internal combustion engine. For example, the vehicle may be a small vehicle such as a passenger car, and the engine may be a spark ignition internal combustion engine, that is, a gasoline engine. Although the illustrated example shows an in-line four-cylinder engine, the cylinder arrangement type, the number of cylinders, and the like of the engine are arbitrary.

  The engine 1 includes an engine body 2, an intake passage 3 and an exhaust passage 4 connected to the engine body 2, a turbocharger 14, and a fuel injection device 5. The engine body 2 includes structural parts such as a cylinder head, a cylinder block, and a crankcase, and movable parts such as a piston, a crankshaft, and a valve housed therein.

  The fuel injection device 5 is a common rail fuel injection device, and includes a fuel injection valve or an injector 7 provided in each cylinder, and a common rail 8 connected to the injector 7. The injector 7 directly injects fuel into the cylinder 9, that is, into the combustion chamber. The common rail 8 stores high pressure fuel injected from the injector 7.

  The intake passage 3 is mainly defined by an intake manifold 10 connected to the engine body 2 (particularly a cylinder head) and an intake pipe 11 connected to the upstream end of the intake manifold 10. The intake manifold 10 distributes and supplies the intake air sent from the intake pipe 11 to the intake ports of each cylinder. The intake pipe 11 is provided with an air cleaner 12, an air flow meter 13, a compressor 14 </ b> C of the turbocharger 14, an intercooler 15, and an electronically controlled intake throttle valve 16 in order from the upstream side. The air flow meter 13 is a sensor for detecting the intake air amount (intake flow rate) per unit time of the engine 1.

  The exhaust passage 4 is mainly defined by an exhaust manifold 20 connected to the engine body 2 (particularly a cylinder head) and an exhaust pipe 21 connected to the downstream side of the exhaust manifold 20. The exhaust manifold 20 collects exhaust gas sent from the exhaust port of each cylinder. A turbine 14 </ b> T of the turbocharger 14 is provided between the exhaust pipe 21 or between the exhaust manifold 20 and the exhaust pipe 21. The exhaust pipe 21 downstream of the turbine 14T is provided with a post-processing member (not shown) for exhaust purification. A total of four post-treatment members are provided in order from the upstream side: an oxidation catalyst, a particulate filter (DPF), a selective reduction type NOx catalyst (SCR), and an ammonia oxidation catalyst. Note that the number, arrangement, type, and the like of the post-processing members can be changed.

  The turbocharger 14 is a variable capacity turbocharger. A nozzle opening variable mechanism 28 that varies the nozzle opening at the turbine inlet is provided, and the nozzle opening variable mechanism 28 is operated by a nozzle actuator 29. The nozzle opening variable mechanism 28 has a plurality of movable nozzle vanes that open and close the nozzles, and the nozzle opening is increased or decreased by opening and closing the movable nozzle vanes simultaneously.

  The engine 1 also includes an EGR device 30. The EGR device 30 includes an EGR passage 31 for returning a part of exhaust gas (referred to as “EGR gas”) in the exhaust passage 4 (especially in the exhaust manifold 20) to the intake passage 3 (particularly in the intake manifold 10). The EGR cooler 32 that cools the EGR gas flowing through the EGR passage 31 and the EGR valve 33 for adjusting the flow rate of the EGR gas are provided.

  The engine 1 also includes a blow-by gas recirculation device 23. The blow-by gas recirculation device 23 introduces blow-by gas in the engine body 2 (particularly in the crankcase) and separates oil from the blow-by gas, an inlet end is connected to the oil separator 24, and an outlet end is And a blow-by gas passage 25 connected to the intake passage 3. The blow-by gas passage 25 circulates the blow-by gas after the oil is separated by the oil separator 24 to the intake passage 3. The outlet end of the blow-by gas passage 25 is connected to the intake passage 3 at a position upstream of the compressor 14C. As a result, the blow-by gas is circulated to the upstream side of the compressor 14C. The outlet end of the blowby gas passage 25 is connected to a position relatively close to the compressor 14C. The blow-by gas recirculation device 23 may include a known PCV (Positive Crankcase Ventilation) valve that opens and closes according to the intake pressure near the outlet end of the blow-by gas passage 25.

  Further, in the present embodiment, an electronic control unit (hereinafter referred to as “ECU”) 100 that constitutes a control unit, a circuit element, or a controller is provided. The ECU 100 controls the entire engine, and includes a CPU, ROM, RAM, input / output ports, a storage device, and the like. The ECU 100 is configured and programmed to control the injector 7, the intake throttle valve 16, the EGR valve 33, and the nozzle actuator 29.

  The ECU 100 constitutes a diagnostic device as defined in the claims.

  Various sensors are connected to the ECU 100. Regarding these sensors, in addition to the air flow meter 13 described above, a rotational speed sensor 40 for detecting the rotational speed (rpm) of the engine and an accelerator opening sensor 41 for detecting the accelerator opening are provided.

  Further, the inlet temperature sensor 47 and the inlet pressure sensor 48 for detecting the temperature and pressure of the intake air at the inlet of the compressor 14C (hereinafter referred to as compressor inlet temperature and compressor inlet pressure), and the temperature of the intake air at the outlet of the compressor 14C. And an outlet temperature sensor 49 and an outlet pressure sensor 50 for detecting the pressure (hereinafter referred to as compressor outlet temperature and compressor outlet pressure), an atmospheric pressure sensor 51 for detecting atmospheric pressure, and a vehicle travel distance are detected. An odometer 52 is provided. The inlet temperature sensor 47 and the inlet pressure sensor 48 are provided at positions downstream of the blow-by gas passage connection position in the intake passage 3. On the other hand, an air flow meter 13 is provided at a position upstream of the connection position.

  In the present embodiment, separate inlet temperature sensor 47 and inlet pressure sensor 48 are provided, but both sensors may be provided in a common and single sensor body. The same applies to the outlet temperature sensor 49 and the outlet pressure sensor 50.

  In addition, a boost pressure sensor 53 for detecting an intake pressure, that is, a boost pressure at a position downstream of the intake throttle valve 16 is provided. The boost pressure is the pressure of the intake air actually sucked into the cylinder 9.

  In the engine 1, the outlet end of the blow-by gas passage 25 is connected to the upstream side of the compressor 14 </ b> C in the intake passage 3. As a result, the mist-like oil mixed in the blow-by gas and not completely separated by the oil separator 24 is circulated into the intake passage 3 together with the blow-by gas.

  Due to the circulating oil, a coking abnormality may occur in the compressor 14C. That is, on the upstream side of the compressor 14C, the oil is still at a low temperature of about room temperature and is a liquid having a relatively low viscosity. However, when the intake air mixed with this oil is compressed by the compressor 14C, and the temperature is increased and the pressure is increased, the oil contained in the intake air is also heated to a high temperature (about 160 to 170 ° C.), and a relatively high viscosity liquid. To denature. Then, this high-viscosity oil adheres to the sliding parts of the compressor wheel and the compressor housing, and increases the sliding resistance. High viscosity oil adheres to the compressor outlet passage on the downstream side of the compressor wheel and partially blocks it. Thus, high-viscosity oil adhering to various places is called coking, and an abnormality of the compressor 14C caused by coking is called a coking abnormality.

  When the coking abnormality occurs, the original performance of the compressor 14C cannot be exhibited. Therefore, it is desirable to detect and deal with the coking abnormality as quickly as possible.

  Therefore, in the present embodiment, as described below, a coking abnormality can be quickly detected. In particular, in the present embodiment, the coking abnormality can be detected by paying attention to the relationship between the operation time of the engine 1 and the degree of decrease in compressor efficiency.

  The efficiency of the compressor 14 </ b> C, that is, the compressor efficiency, decreases due to natural degradation as the cumulative operation time from when the engine 1 is new becomes longer. Therefore, there is a certain correlation between the operating time of the engine 1 and the compressor efficiency.

  On the other hand, when the coking abnormality occurs, the actual compressor efficiency value is lower than the compressor efficiency value commensurate with the operation time of the engine 1. Therefore, the ECU 100 as the diagnostic device of the present embodiment is configured to determine whether or not a coking abnormality has occurred based on the operation time of the engine 1 and the compressor efficiency.

  In this case, it is possible to use the correlation value instead of the operation time of the engine 1, and it may be more convenient to do so. In this embodiment, the travel distance of the vehicle that is the correlation value is used instead of the driving time. By doing so, it is not necessary to separately measure the driving time, and the detection value of the odometer 52 normally mounted on the vehicle can be used, which is advantageous for simplification of the apparatus. In addition, as the correlation value, an integrated fuel injection amount that is an integrated value of the fuel injection amount of the injector 7 or an integrated intake air amount that is an integrated value of the intake air amount detected by the air flow meter 13 is used. Is possible.

  ECU 100 calculates actual compressor efficiency ηa (%) of compressor 14C according to the following equation.

Here, T _1c is the compressor inlet temperature detected by the inlet temperature sensor 47, P _1c is the compressor inlet pressure detected by the inlet pressure sensor 48, T _2c is the compressor outlet temperature detected by the outlet temperature sensor 49, P _2c Is the compressor outlet pressure detected by the outlet pressure sensor 50, and P ₀ is the atmospheric pressure detected by the atmospheric pressure sensor 51.

  On the other hand, ECU 100 stores in advance a relationship between travel distance L and compressor efficiency ηm, and determines whether or not a coking abnormality has occurred using this relationship. The compressor efficiency ηm here is a compressor efficiency in a healthy state where no coking abnormality has occurred, and is a value obtained in advance through an actual machine test or the like.

  Specifically, the ECU 100 stores in advance a map that defines the relationship between the travel distance L and the compressor efficiency ηm, as indicated by a solid line in FIG. 2, and whether or not a coking abnormality has occurred using this map. Determine. Hereinafter, for convenience, the compressor efficiency ηm on the relationship or the map is referred to as an estimated compressor efficiency. As shown in the figure, the estimated compressor efficiency ηm tends to decrease due to natural degradation as the travel distance L increases.

  As shown in FIG. 2, the ECU 100 acquires an estimated compressor efficiency ηm (for example, ηm1) corresponding to the actual travel distance L (for example, L1) detected by the odometer 52 from the map. Further, the actual compressor efficiency ηa (indicated by a broken line, for example, ηa1) is calculated from the previous equation. The ECU 100 calculates a difference Δη (= ηm−ηa) between the estimated compressor efficiency ηm and the actual compressor efficiency ηa, and compares the difference Δη with a predetermined threshold value Δηs.

  ECU 100 determines that no coking abnormality has occurred when difference Δη is equal to or smaller than threshold value Δηs (Δη ≦ Δηs). On the other hand, when difference Δη is greater than threshold value Δηs (Δη> Δηs), ECU 100 determines that a coking abnormality has occurred. As a result, when a coking abnormality occurs, it can be promptly detected. As described above, the threshold value Δηs is set as the value of the difference Δη that defines the boundary between when the coking abnormality occurs and when it does not occur. More specifically, the threshold value Δηs is set as the maximum allowable value of the amount of decrease when the actual compressor efficiency ηa decreases below the estimated compressor efficiency ηm at the same travel distance L.

  When it is determined that a coking abnormality has occurred, the ECU 100 activates a warning device (warning lamp or the like) (not shown) to warn the user. As a result, the user can be encouraged to perform inspection and maintenance necessary to eliminate the coking abnormality, and the coking abnormality can be eliminated early. Note that the cause of the caulking abnormality may be a failure of the oil separator 24 or the PCV valve. As measures necessary for eliminating the coking abnormality, it is conceivable to disassemble and maintain the blow-by gas recirculation device 23 and the turbocharger 14.

  Incidentally, the ECU 100 feedback-controls the nozzle actuator 29 so that the actual boost pressure detected by the boost pressure sensor 53 approaches the target boost pressure determined according to the engine operating state (for example, the engine rotation speed and the target fuel injection amount). . As a result, the nozzle opening variable mechanism 28, the nozzle opening, and hence the boost pressure are feedback-controlled, and the actual boost pressure is brought close to the target boost pressure.

  When the coking abnormality occurs, the compressor efficiency is lower than when the coking abnormality does not occur, and the actual boost pressure decreases even if the same nozzle opening is controlled. For this reason, in order to make the actual boost pressure approach the target boost pressure, the nozzle opening degree is controlled to a smaller value, thereby increasing the engine back pressure. Then, pump loss increases and fuel consumption deteriorates.

  According to the present embodiment, when a coking abnormality occurs, it can be detected and resolved early, so that it is possible to suppress the vehicle from continuing to travel in a state where fuel consumption has deteriorated due to the coking abnormality.

  Next, referring to FIG. 3, the routine of the diagnostic process in the present embodiment will be described. The illustrated routine is repeatedly executed by the ECU 100 at every predetermined calculation cycle τ.

  The calculation cycle τ can be set in units of time, but in the present embodiment, it is set in units of travel distance in alignment with the map of FIG. The calculation cycle τ is, for example, 1 km, and the ECU 100 executes a routine every time the actual travel distance L increases by τ = 1 km.

In step S101, the ECU 100 detects the actual compressor inlet temperature T _1c , compressor inlet pressure P _1c , compressor outlet temperature T _2c , compressor outlet pressure P _2c , atmospheric pressure P ₀ , and travel distance L detected by the corresponding sensors. Get the value.

  Next, in step S102, the ECU 100 calculates the actual compressor efficiency ηa from the previous equation.

  In step S103, the ECU 100 calculates a value of the estimated compressor efficiency ηm corresponding to the value of the travel distance L from the map of FIG.

  In step S104, the ECU 100 calculates a difference Δη (= ηm−ηa) between the estimated compressor efficiency ηm and the actual compressor efficiency ηa.

  In step S105, the ECU 100 compares the difference Δη with a predetermined threshold value Δηs. Specifically, ECU 100 determines whether or not difference Δη is greater than threshold value Δηs.

  When the difference Δη is equal to or smaller than the threshold value Δηs (Δη ≦ Δηs), the ECU 100 immediately ends the routine. Thus, ECU 100 substantially determines that no coking abnormality has occurred.

  On the other hand, when the difference Δη is greater than the threshold value Δηs (Δη> Δηs), the ECU 100 substantially determines that a coking abnormality has occurred, and proceeds to step S106 to activate the warning device and execute a warning. This can prompt the user for necessary maintenance.

  As mentioned above, although embodiment of this indication was described in detail, this indication can also be applied to other embodiments as follows.

  (1) For example, the value of the threshold value Δηs can be changed according to the engine operation time or a correlation value thereof, for example, the travel distance L. As shown in FIG. 2, the estimated compressor efficiency ηm decreases due to natural deterioration as the travel distance L increases. Therefore, by reducing the value of the threshold value Δηs as the travel distance L increases, the ratio of the threshold value Δηs to the estimated compressor efficiency ηm can be kept constant in accordance with the decrease in the estimated compressor efficiency ηm. . As a result, it is possible to more appropriately determine whether or not the coking abnormality has occurred by further taking into account the decrease in efficiency due to natural degradation.

  (2) The actual compressor efficiency ηa is not necessarily calculated from the previous equation, and can be calculated by any method including a known method.

  (3) The ratio of the estimated compressor efficiency ηm and the actual compressor efficiency ηa may be compared with a predetermined threshold value to determine whether or not a coking abnormality has occurred.

  The embodiment of the present disclosure is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present disclosure defined by the claims. Therefore, the present disclosure should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present disclosure.

1 Internal combustion engine
3 Intake passage 14 Turbocharger 14C Compressor 25 Blow-by gas passage 100 Electronic control unit (ECU)

Claims (5)

A diagnostic device for an internal combustion engine,
The internal combustion engine
A turbocharger compressor installed in the intake passage;
A blow-by gas passage connected to the intake passage at a position upstream of the compressor;
With
The diagnostic device is configured to determine whether or not a coking abnormality has occurred in the compressor based on an operation time of the internal combustion engine or a correlation value thereof and a compressor efficiency of the compressor. A diagnostic apparatus for an internal combustion engine. The diagnostic device for an internal combustion engine according to claim 1, wherein a relationship between an operating time of the internal combustion engine or a correlation value thereof and the compressor efficiency is stored in advance, and whether or not the coking abnormality has occurred is determined using the relationship. . The compressor efficiency corresponding to the actual operation time or its correlation value is acquired from the relationship, and the actual compressor efficiency is calculated, and the difference between the compressor efficiency acquired from the relationship and the calculated actual compressor efficiency is calculated. The diagnostic apparatus for an internal combustion engine according to claim 2, wherein the difference is compared with a predetermined threshold value to determine whether or not the coking abnormality has occurred. The diagnostic apparatus for an internal combustion engine according to claim 3, wherein the actual compressor efficiency is calculated based on a compressor inlet temperature, a compressor outlet temperature, a compressor inlet pressure, a compressor outlet pressure, and an atmospheric pressure. The internal combustion engine is mounted on a vehicle, and the diagnostic device determines whether or not the coking abnormality has occurred based on a travel distance of the vehicle that is a correlation value of an operation time of the internal combustion engine and the compressor efficiency. The diagnostic device for an internal combustion engine according to any one of claims 1 to 4.

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