Abnormality diagnosis method for vehicle and abnormality diagnosis device for vehicle

Abstract

A vehicle has an internal combustion engine (1), a throttle valve (6) disposed in an intake passage (3) to control an intake air amount, a second passage (33) connected to the intake passage (3) on an upstream side of the throttle valve (6) to be able to introduce fresh air into a crankcase (39), a third passage (34) connected to the intake passage (3) on a downstream side of the throttle valve (6) to be able to introduce blow-by gas into the intake passage (3), and a pressure sensor (53) to be able to detect an intake pressure in the intake passage (3) on the downstream side of the throttle valve (6). When the internal combustion engine (1) is motored in a state where the throttle valve (6) is reduced to a prescribed opening degree, it is diagnosed whether or not the third passage (34) is abnormal based on a motoring intake pressure detected by the pressure sensor (53).

Description

Technical Field

[0001] This invention relates to a method and device for diagnosing vehicle malfunctions. Background Technology

[0002] For example, Patent Document 1 discloses an internal combustion engine having a blow-by passage and a purification passage. The blow-by passage connects a portion of the intake passage downstream of the throttle valve, i.e., the downstream throttle passage, to the crankcase. The purification passage connects a storage container for adsorbing evaporated fuel from the fuel tank to the aforementioned downstream throttle passage.

[0003] In this patent document 1, the following abnormality diagnosis is performed: when the deceleration fuel cut-off is executed, which stops the fuel supply to the combustion chamber of the internal combustion engine as the vehicle decelerates, the above-mentioned purification valve is closed, and the flow rate of the blow-by gas introduced into the downstream passage of the throttling through the blow-by passage when the purification valve is closed is used to determine whether the blow-by passage has become abnormal.

[0004] Patent Document 1 estimates the flow rate of the gas introduced into the downstream passage of the throttle valve through the gas flow path based on the air flow rate (throttle flow rate) detected by the air flow sensor and the pressure of the intake air flowing through the downstream passage of the throttle valve (downstream pressure) detected by the intake pressure sensor.

[0005] In Patent Document 1, the intensity of the strong negative pressure formed in the downstream passage of the throttling system during the aforementioned deceleration fuel cut-off is affected by the vehicle's operating conditions (e.g., vehicle speed). Therefore, when using the pressure (negative pressure) of the downstream passage of the throttling system to diagnose whether there is an abnormality in the blow-by passage, it is difficult to set a threshold for comparison with the pressure (negative pressure) of the downstream passage of the throttling system.

[0006] Therefore, in Patent Document 1, the flow rate of the gas leaking through is used as a parameter for diagnosing the abnormality of the aforementioned gas leaking pathway, and the detection value of the aforementioned intake pressure sensor cannot be directly used as a parameter for diagnosing the abnormality.

[0007] In other words, there is room for further improvement in order to diagnose whether there are any abnormalities in the pathway for introducing gas into the intake passage using parameters other than the flow rate of the gas.

[0008] Patent Document 1: Japanese Patent Application Publication No. 2022-167629 Summary of the Invention

[0009] This invention relates to a diagnostic method for a vehicle comprising: an internal combustion engine; a first intake throttle valve disposed in the intake passage of the internal combustion engine for controlling the intake air volume of the internal combustion engine; a fresh air inlet passage connected to the intake passage upstream of the first intake throttle valve for introducing fresh air into the crankcase; a blow-by gas return passage connected to the intake passage downstream of the first intake throttle valve for introducing blow-by gas into the intake passage; and a pressure sensor capable of detecting the intake pressure in the intake passage downstream of the first intake throttle valve. When the internal combustion engine is driven by an electric motor with the first intake throttle valve reduced to a predetermined opening, the method diagnoses whether there is any abnormality in the blow-by gas return passage based on the intake pressure detected by the pressure sensor during motor drive.

[0010] When the internal combustion engine is driven by the electric motor, the pressure change caused by the abnormality of the blow-by gas return path is stable. Therefore, the abnormality of the blow-by gas return path can be diagnosed based on the pressure of the intake passage. Attached Figure Description

[0011] Figure 1 This is an explanatory diagram schematically illustrating the system structure of an internal combustion engine according to the first embodiment of the present invention.

[0012] Figure 2 This is an illustrative diagram that schematically illustrates the correlation between the differential pressure threshold, the first pressure value, and the intake air volume.

[0013] Figure 3 This is a flowchart illustrating an example of the control process during abnormal diagnosis of a gas reflux system.

[0014] Figure 4 This is an explanatory diagram schematically illustrating the system structure of an internal combustion engine in the second embodiment of the present invention. Detailed Implementation

[0015] Hereinafter, an embodiment of the present invention will be described in detail based on the accompanying drawings.

[0016] Figure 1 This is an explanatory diagram schematically illustrating the system structure of the internal combustion engine 1 in the first embodiment of the present invention.

[0017] The vehicle involved in this invention is, for example, a so-called series hybrid vehicle that does not use an internal combustion engine 1 as its power source. In such a vehicle, for example, if the remaining battery capacity of the onboard battery (not shown) decreases, the internal combustion engine 1 is driven to generate electricity via a generator (not shown) in order to charge the battery. This generator converts the rotational energy generated by the internal combustion engine 1 into electrical energy to charge, for example, the battery. Furthermore, this generator also functions as an electric motor to drive the internal combustion engine 1, enabling motor-driven operation of the internal combustion engine 1. The generator can also function as a starter motor for the internal combustion engine 1. Moreover, the electricity generated by the generator can be supplied directly to a drive motor that drives the vehicle's drive wheels according to the operating conditions, without charging the battery.

[0018] The internal combustion engine 1 is, for example, a multi-cylinder spark-ignition gasoline internal combustion engine. Intake air is introduced into each cylinder of the internal combustion engine 1 via the intake manifold 2, which forms part of the intake passage 3.

[0019] The intake passage 3 is equipped with an air filter 4 to capture foreign objects in the intake air, an air flow meter 5 to detect the amount of intake air, an electric throttle valve 6, an electric pressure control valve 7 located upstream of the throttle valve 6, and a pressure sensor 53.

[0020] The air flow meter 5, which functions as an intake air volume detection sensor, is located upstream of the pressure control valve 7. The air flow meter 5 also incorporates a temperature sensor to detect the intake air temperature.

[0021] Air filter 4 is located upstream of air flow meter 5.

[0022] In the first embodiment, the throttle valve 6 functions as a first intake throttle valve, controlling the amount of air intake into the internal combustion engine 1. In the first embodiment, the pressure control valve 7 functions as a second intake throttle valve, controlling the intake pressure upstream of the compressor 10 (described later). That is, the pressure control valve 7 can generate negative pressure upstream of the throttle valve 6.

[0023] Throttle valve 6 and pressure control valve 7 can change (control) their opening degree according to the control signal from engine control module (ECM) 8. In the intake passage 3, which is located downstream of throttle valve 6, a pressure sensor 53 is provided to detect the intake pressure in the intake passage.

[0024] Additionally, the internal combustion engine 1 includes a turbocharger 9. The turbocharger 9 includes a compressor 10 disposed in the intake passage 3 and a turbine (not shown) disposed in the exhaust passage. The compressor 10 and the turbine are mounted coaxially and rotate integrally. The compressor 10 is positioned upstream of the throttle valve 6 and downstream of the pressure control valve 7.

[0025] An intercooler 12 is provided upstream of the throttle valve 6 in the intake passage 3. The intercooler 12 is located downstream of the compressor 10 and is configured to cool the intake air compressed (pressurized) by the compressor 10 to improve filling efficiency.

[0026] Here, an EGR passage (not shown) is connected downstream of the pressure control valve 7. One end of this EGR passage is connected to the aforementioned exhaust passage, and the other end is connected to the intake passage 3 at a position that is downstream of the pressure control valve 7 and upstream of the compressor 10. The aforementioned EGR passage enables exhaust gas recirculation (EGR) by returning a portion of the exhaust gas from the aforementioned exhaust passage to the intake passage 3.

[0027] also, Figure 1 The number 23 in the diagram refers to the intake manifold located downstream of the throttle valve 6.

[0028] A blow-by gas recirculation system 31 is connected to the intake passage 3 for treating blow-by gas, which is introduced into the intake passage 3. The blow-by gas recirculation system 31 is composed of multiple passages connected to the intake passage 3 at a position downstream of the air flow meter 5. Blow-by gas is combustion gas that leaks from the combustion chamber 38 of the internal combustion engine 1 to the crankcase 39 of the internal combustion engine 1 through the gap between the cylinder and the piston.

[0029] The gas reflux system 31 has a first passage 32 formed by a tubular first annular component, a second passage 33 formed by a tubular second annular component, a third passage 34 formed by a tubular third annular component, a one-way valve 35, and a PCV valve 37.

[0030] The first passage 32 connects (communicates) the position between the throttle valve 6 and the pressure control valve 7 in the intake passage 3 to the crankcase 39 of the internal combustion engine 1. One end of the first passage 32 is connected to the position between the throttle valve 6 and the pressure control valve 7 in the intake passage 3, and the other end is connected to the internal combustion engine 1 via a one-way valve 35. Specifically, one end of the first passage 32 is connected to the position between the compressor 10 and the pressure control valve 7 in the intake passage 3. The first passage 32 can introduce blow-by gas from the crankcase 39 into the intake passage 3. Specifically, the first passage 32 can introduce blow-by gas into the intake passage 3 by reducing the opening of the pressure control valve 7 (closing the valve) and creating negative pressure downstream of the pressure control valve 7.

[0031] The one-way valve 35 has the function of allowing flow from the crankcase 39 toward the intake passage 3 and prohibiting flow from the intake passage 3 toward the crankcase 39.

[0032] The second passage 33 connects (makes them connected) the position between the pressure control valve 7 and the air flow meter 5 in the intake passage 3 and the crankcase 39 of the internal combustion engine 1. One end of the second passage 33 is connected to the position between the pressure control valve 7 and the air flow meter 5 in the intake passage 3, and the other end is connected to the internal combustion engine 1. The second passage 33 constitutes a fresh air introduction passage, which can introduce fresh air (air) into the crankcase 39 of the internal combustion engine 1.

[0033] The third passage 34 connects (communicates) a position in the intake passage 3 downstream of the throttle valve 6 to the crankcase 39 of the internal combustion engine 1. One end of the third passage 34 is connected to the position in the intake passage 3 downstream of the throttle valve 6, and the other end is connected to the internal combustion engine 1 via the PCV valve 37. The third passage 34 corresponds to the blow-by gas return passage in the first embodiment, and can guide blow-by gas in the crankcase 39 into the intake passage 3.

[0034] PCV valve 37 acts as a blow-by gas control valve, controlling the flow rate of gas in the third passage 34. PCV valve 37 is, for example, a known differential pressure actuated valve, installed in the internal combustion engine 1, and operates by opening when the pressure difference between the inlet pressure on the crankcase 39 side and the outlet pressure on the intake passage 3 side is large. Specifically, PCV valve 37 prevents external gas from flowing back through the third passage 34 from the intake passage 3 into the crankcase 39, and, based on the pressure difference, discharges blow-by gas from the crankcase 39 into the intake passage 3. That is, the internal combustion engine 1 can utilize the negative pressure downstream of the throttle valve 6 to return the blow-by gas to the intake passage 3 via PCV valve 37 and the third passage 34.

[0035] ECM 8 is a known digital computer with a CPU, ROM, RAM, and input / output interfaces. In addition to the detection signal from the air flow meter 5 mentioned above, ECM 8 also receives detection signals from various sensor components, including a crankshaft angle sensor 51 for detecting crankshaft angle, an accelerator pedal opening sensor 52 for detecting accelerator pedal pressure, a pressure sensor 53 for detecting pressure in the intake manifold 2, an atmospheric pressure sensor 54 for detecting atmospheric pressure, a first opening sensor 55 for detecting the opening of the throttle valve 6, and a second opening sensor 56 for detecting the opening of the pressure control valve 7.

[0036] The crankshaft angle sensor 51 can detect the engine speed of the internal combustion engine 1. The accelerator opening sensor 52 can detect the operating speed of the accelerator pedal, i.e., the accelerator change speed.

[0037] ECM 8 controls the operation of the internal combustion engine 1 based on detection signals from various sensor arrays. Specifically, if the remaining battery charge of the aforementioned battery decreases, the internal combustion engine 1 is driven to charge the battery.

[0038] Here, in cases where there are abnormalities in the blow-by gas return system 31, such as one end of the third tubular component constituting the third passage 34 detaching from the intake pipe constituting the intake passage 3, the other end of the third tubular component detaching from the PCV valve 37, the third tubular component opening, or the PCV valve 37 detaching from the internal combustion engine 1, air enters from the location of the abnormality.

[0039] Therefore, as a vehicle anomaly diagnosis, the ECM 8 of the diagnostic unit uses the pressure within the intake passage 3 to diagnose whether there is any abnormality in the blow-by gas recirculation system 31. The anomaly diagnosis of the blow-by gas recirculation system 31 in the first embodiment is performed, for example, on the onboard internal combustion engine 1 used for power generation. This anomaly diagnosis of the blow-by gas recirculation system 31 is performed, for example, once during one driving cycle of the vehicle. Here, one driving cycle is, for example, from when the vehicle's ignition switch is turned on until the ignition switch is turned off.

[0040] When the ECM 8 drives the internal combustion engine 1 with the throttle valve 6 reduced to a specified opening (valve closed state), it diagnoses whether there is any abnormality in the blow-by gas recirculation system 31 based on the pressure detected by the pressure sensor 53. Specifically, if the absolute value of the difference between the pressure detected by the pressure sensor 53 when the internal combustion engine 1 is driven by the electric motor and the pressure detected by the pressure sensor 53 when the internal combustion engine 1 is stopped is less than a specified pressure difference judgment threshold, the ECM 8 diagnoses that there is an abnormality in the third passage 34 of the blow-by gas recirculation system 31.

[0041] Furthermore, the aforementioned opening degree refers to a so-called closed valve state of approximately a few degrees. Even when the throttle valve 6 of the internal combustion engine 1 is in a closed valve state, it does not actually completely cut off the inflow of intake air.

[0042] When the specified first condition is met, ECM 8 detects the intake pressure during motor-driven operation via pressure sensor 53. The first condition is a condition that allows pressure measurement in the intake manifold 2 during motor-driven operation of the internal combustion engine 1, in order to diagnose abnormalities in the blow-by gas recirculation system 31. The first condition includes, for example, motor-driven operation, the cessation of fuel supply to the internal combustion engine 1, the internal combustion engine speed of the internal combustion engine 1 being a preset first speed (e.g., around 1500 rpm), the throttle valve 6 being reduced to a specified opening (e.g., the valve opening being closed at around a few degrees), and the intake air volume being less than or equal to a preset diagnostic air volume Q. Motor-driven operation can be implemented and utilized, for example, upon request from an on-board diagnostic system (OBD) or the like, or it can be implemented after the power generation by the internal combustion engine 1 has ended, in order to diagnose abnormalities in the blow-by gas recirculation system 31.

[0043] If the internal combustion engine 1 is driven by an electric motor, the fuel supply to the internal combustion engine 1 is stopped, the throttle valve 6 is closed, and the intake air volume detected by the air flow meter 5 is less than or equal to a preset amount. Then, the ECM 8 is set to condition 1, and the intake pressure (intake pressure when driven by an electric motor) in the intake manifold 2 is continuously measured for a specified time (specified period). The average pressure during this specified time (specified period), i.e., the average intake pressure when driven by an electric motor, is recorded. The average intake pressure when driven by an electric motor is the average value of the intake pressures measured when condition 1 is met.

[0044] Furthermore, if condition 1 is met, the ECM 8 measures the environmental conditions during motor operation—namely, atmospheric pressure, intake temperature, and intake volume—simultaneously with the measurement of the intake pressure within the intake manifold 2. The ECM 8 also records the average atmospheric pressure, average intake temperature, and average intake volume during motor operation for a specified period of time during which the intake pressure (intake pressure during motor operation) within the intake manifold 2 is continuously measured. The average atmospheric pressure, average intake temperature, and average intake volume during motor operation are the average values ​​of the atmospheric pressure, intake temperature, and intake volume measured when condition 1 is met.

[0045] After recording the average intake pressure during motor operation, if the specified second condition is met, the ECM 8 detects the intake pressure at the point of stop via pressure sensor 53. The second condition is a condition that allows pressure measurement in the intake manifold 2 when the internal combustion engine 1 is stopped, in order to diagnose abnormalities in the blow-by gas recirculation system 31. The second condition may include, for example, within a specified time after the intake pressure measurement during motor operation has ended, the fuel supply to the internal combustion engine 1 has stopped, the internal combustion engine speed of the internal combustion engine 1 is less than or equal to a preset second speed (e.g., 100 rpm), and the vehicle speed is less than or equal to a preset speed.

[0046] If, within a specified time after the intake pressure measurement during motor-driven operation has ended, the fuel supply to the internal combustion engine 1 has stopped, the internal combustion engine speed of the internal combustion engine 1 is less than or equal to the second speed, and the vehicle speed is less than or equal to the preset specified speed, then the ECM 8 is set to the second condition being met, and the intake pressure (intake pressure at the time of stop) in the intake manifold 2 is continuously measured for a specified time (specified period), and the average pressure during that specified time (specified period), i.e., the average intake pressure at the time of stop, is recorded.

[0047] Furthermore, if condition 2 is met, the ECM 8 measures the environmental conditions at which the internal combustion engine 1 is stopped, namely atmospheric pressure, intake temperature, and intake volume, simultaneously with the measurement of the intake pressure in the intake manifold 2. The ECM 8 also records the average atmospheric pressure, average intake temperature, and average intake volume at the time of stopping for a specified period during which the intake pressure (intake pressure at the time of stopping) in the intake manifold 2 is continuously measured.

[0048] If the specified third condition is met, and the absolute value of the pressure difference between the standard average intake pressure during motor operation (described later) and the standard average intake pressure at the stop (described later), i.e., the first pressure value, is less than the specified pressure difference judgment threshold, then the ECM 8 diagnoses (determines) that there is an abnormality in the third passage 34. The third condition is a permissible condition for diagnosing abnormalities in the third passage 34 using the first pressure value and the pressure difference judgment threshold, in order to diagnose abnormalities in the blow-by gas recirculation system 31. Examples of the third condition include: the difference between the average atmospheric pressure during motor operation and the average atmospheric pressure at the stop being within a specified value; the difference between the average intake temperature during motor operation and the average intake temperature at the stop being within a specified value; and the sensor components used for diagnosing abnormalities in the blow-by gas recirculation system 31 not malfunctioning.

[0049] ECM 8, by setting a third condition, will not perform diagnostics when the environmental conditions change significantly during the measurement of intake pressure while the motor is running and when the measurement of intake pressure is stopped.

[0050] If condition 3 is met, the ECM 8 will correct the recorded average intake pressure during motor operation and average intake pressure at rest to values ​​under specified standard environmental conditions. That is, if condition 3 is met, the ECM 8 will correct (convert) the average intake pressure during motor operation to the value under standard environmental conditions, i.e., the standard average intake pressure during motor operation, and will also correct (convert) the average intake pressure at rest to the value under standard environmental conditions, i.e., the standard average intake pressure at rest. Standard environmental conditions, for example, refer to atmospheric pressure at standard atmospheres (1 atmosphere) and intake temperature at standard intake temperature (e.g., 25°C).

[0051] Furthermore, ECM 8 uses the average intake volume when the motor is driven to calculate the differential pressure threshold. Figure 2 This is an illustrative diagram schematically showing the correlation between the differential pressure judgment threshold, the first pressure value, and the intake air volume detected by the air flow meter 5. The fault diagnosis of the blow-by gas recirculation system 31 is performed in the fault diagnosis implementation area where the intake air volume becomes less than or equal to the diagnostic air volume Q from the first condition onwards.

[0052] Regarding the gas return system 31, if there is no abnormality in the third passage 34, the pressure difference in the intake manifold 2, i.e., the first pressure value, increases when the motor is running and when it is stopped. If there is an abnormality in the third passage 34, the pressure difference in the intake manifold 2, i.e., the first pressure value, decreases when the motor is running and when it is stopped.

[0053] exist Figure 2 In the diagram, characteristic line C1, represented by a solid line, shows the first pressure value under the condition that the third passage 34 is normal. Figure 2 In the diagram, characteristic line C2, represented by a thin dashed line, shows the first pressure value under the condition that the third passage 34 is abnormal. Figure 2 In the diagram, characteristic line C3, represented by a thick dashed line, indicates the differential pressure threshold.

[0054] The differential pressure threshold is set to take into account various fluctuations and become a value between characteristic line C1 and characteristic line C2. That is, the differential pressure threshold is set to take into account various fluctuations and be greater than the value that the first pressure value can take when there is an anomaly in the third passage 34. In addition, the differential pressure threshold is set to be smaller as the intake air volume increases.

[0055] Furthermore, the first pressure value decreases as the elevation increases. Therefore, by setting the differential pressure threshold such that a higher elevation results in a lower differential pressure threshold, abnormal diagnosis of the gas reflux system 31 can be performed regardless of the elevation. That is, the differential pressure threshold and the first pressure value can be corrected based on the elevation. For example, they can be corrected so that a higher elevation results in a lower differential pressure threshold, or they can be corrected so that a higher elevation results in a higher first pressure value.

[0056] Furthermore, fluctuations in the pressure sensor 53 are eliminated by using the pressure difference (difference) between the intake pressure when the motor is driven and the intake pressure when the internal combustion engine 1 is stopped.

[0057] If the first pressure value is greater than or equal to the calculated differential pressure threshold, ECM 8 determines that there is no abnormality in the third passage 34 and the gas reflux system 31. Conversely, if the first pressure value is less than the calculated differential pressure threshold, ECM 8 determines that there is some abnormality in the third passage 34 and the gas reflux system 31.

[0058] If the determination that there is an abnormality in the blow-by gas recirculation system 31 continues for two driving cycles, the ECM 8 will notify the driver by illuminating a warning light.

[0059] The abnormality diagnosis of the blow-by gas recirculation system 31 in the first embodiment described above is performed when the internal combustion engine 1 is driven by the electric motor. Therefore, the pressure change (relative to the normal pressure change) caused by the abnormality of the third passage 34 is stable. Thus, the abnormality of the third passage 34 (blow-by gas recirculation passage) can be diagnosed based on the pressure of the intake passage 3.

[0060] Unlike the crankcase 39, the intake passage 3 is a closed space where the internal combustion engine 1 pumps air for diagnostic purposes. As a result, even in abnormal conditions (detachment, opening), the negative pressure develops well and is difficult to show a difference from the normal negative pressure.

[0061] On the other hand, to diagnose the development of negative pressure, if the goal is to maintain a constant internal combustion engine speed through combustion-driven rotation, then in cases of abnormalities such as the PCV valve 37 detaching or the third tubular component detaching, the intake air volume may increase, potentially leading to unstable internal combustion engine speed and preventing the desired negative pressure development under abnormal conditions. Furthermore, if the goal is to transmit wheel rotation to the engine to maintain a constant internal combustion engine speed, in vehicles with transmissions such as stepped automatic transmissions (AT), the engine speed may become inconsistent with changes in vehicle speed. In vehicles with continuously variable transmissions (CVTs), transmitting wheel rotation to the engine to maintain a constant engine speed requires changing the gear ratio, which may affect drivability and complicate control, preventing the pressure from becoming as constant as intended, resulting in unstable pressure under normal conditions. In such cases, to prevent misdiagnosis, measures such as increasing the margin of the aforementioned differential pressure threshold are needed, potentially making diagnosis difficult or reducing diagnostic accuracy.

[0062] In contrast, during motor-driven operation, the engine is not affected by changes in the amount of air intake or vehicle speed, nor does it affect its performance. Therefore, the internal combustion engine speed can be kept stable and constant. Even in situations where the negative pressure in the intake passage 3 is well-developed and difficult to differ from the normal negative pressure, as long as the internal combustion engine 1 is pumped by the motor, the pressure of the intake passage 3 as envisioned in both abnormal and normal conditions can be stably obtained. Therefore, high-precision diagnosis can be achieved using the output of a general-purpose intake pressure sensor, i.e., pressure sensor 53.

[0063] Therefore, the pressure sensor 53 is not designed for diagnosing abnormalities in the third passage 34 (blow-through gas return passage), and existing sensors that detect the intake pressure within the intake manifold 2 can be used.

[0064] If the pressure of intake passage 3 is set as the diagnostic parameter for diagnosing abnormalities in the third passage 34, then the abnormality diagnosis of the blow-by gas recirculation system 31 can be performed using a general intake pressure sensor, i.e., pressure sensor 53, without the need for additional sensors.

[0065] Furthermore, making it easier to stabilize the internal combustion engine speed at a constant level means that even without closing the second passage 33, the negative pressure in the intake passage 3 can be fully developed under normal conditions (when there is no abnormality in the third passage 34). This also provides the option of not setting a diagnostic valve, such as one that closes the valve when diagnosing whether there is an abnormality in the third passage 34, in the second passage 33. That is, by performing abnormality diagnosis of the third passage 34 based on the pressure in the intake passage 3 when driven by the motor, the ECM 8 can perform abnormality diagnosis of the blow-by gas return system 31 even if a diagnostic valve that closes the valve when diagnosing whether there is an abnormality in the third passage 34 is not set in the second passage 33.

[0066] Figure 3 This is a flowchart illustrating an example of the control process when performing abnormal diagnosis of the gas reflux system 31.

[0067] In step S1, it is determined whether an anomaly diagnosis of the blow-by gas recirculation system 31 was performed during the current driving cycle. If, in step S1, it is determined that an anomaly diagnosis of the blow-by gas recirculation system 31 was performed during the current driving cycle, the current routine ends. If, in step S1, it is determined that an anomaly diagnosis of the blow-by gas recirculation system 31 was not performed during the current driving cycle, the process proceeds to step S2.

[0068] In step S2, it is determined whether the intake air pressure or environmental conditions (atmospheric pressure, etc.) measured when the first condition is met, i.e., various parameters when the motor is driven, have been recorded in the current driving cycle. If, in step S2, the various measured values ​​measured when the first condition is met are not recorded, proceed to step S3. If, in step S2, the various measured values ​​measured when the first condition is met are recorded, proceed to step S6.

[0069] In step S3, it is determined whether the first condition is true. If the first condition is true in step S3, proceed to step S4. If the first condition is false in step S3, end the current routine.

[0070] In step S4, the intake pressure is recorded when the motor is driven.

[0071] In step S5, the environmental conditions during motor operation are recorded. The environmental conditions during motor operation refer to atmospheric pressure, intake air temperature, and intake air volume.

[0072] In step S6, it is determined whether the second condition is true. If the second condition is true in step S6, proceed to step S7. If the second condition is false in step S6, end the current routine.

[0073] In step S7, the intake pressure at the time of stopping is recorded.

[0074] In step S8, the environmental conditions when the internal combustion engine 1 stops are recorded. The environmental conditions when the internal combustion engine 1 stops refer to atmospheric pressure, intake air temperature, and intake air volume.

[0075] In step S9, it is determined whether the third condition is true. If the third condition is true in step S9, proceed to step S10. If the third condition is false in step S9, proceed to step S12.

[0076] In step S10, the intake pressure when the motor is running and the intake pressure when it is stopped are corrected to values ​​under standard environmental conditions. That is, in step S10, various parameters such as the intake pressure when the motor is running and the intake pressure when it is stopped are corrected to values ​​based on standard environmental conditions.

[0077] In step S11, various parameters, after being corrected to values ​​based on standard environmental conditions, are used to determine whether there is any abnormality in the gas return system 31.

[0078] In step S12, various parameters such as intake pressure when the motor is driven, intake pressure when stopped, and various environmental conditions recorded when the first and second conditions are met in the current driving cycle are cleared.

[0079] Hereinafter, other embodiments of the present invention will be described. Furthermore, structural elements identical to those in the first embodiment described above will be labeled with the same reference numerals, and repeated descriptions will be omitted.

[0080] Figure 4 This is a schematic diagram illustrating the general system structure of the internal combustion engine 1 in the second embodiment of the invention.

[0081] The system structure of the internal combustion engine 1 in the second embodiment is roughly the same as that in the first embodiment described above, but the third passage 34 in the first embodiment is omitted.

[0082] Furthermore, in this second embodiment, the pressure control valve 7 is equivalent to the first intake throttle valve, and the first passage 32 is equivalent to the gas return passage. A pressure sensor 53 is provided in the intake passage 3, which is located downstream of the pressure control valve 7, to detect the intake pressure within the intake passage.

[0083] In the second embodiment, the ECM 8, which is equivalent to the diagnostic unit, diagnoses whether there is an abnormality in the blow-by gas recirculation system 31 based on the pressure detected by the pressure sensor 53 when the internal combustion engine 1 is driven by an electric motor with the throttle valve 6 fully open and the pressure control valve 7 reduced to a specified opening degree (valve closed state). In the second embodiment, if the absolute value of the difference between the pressure detected by the pressure sensor 53 when the internal combustion engine 1 is driven by an electric motor and the pressure detected by the pressure sensor 53 when the internal combustion engine 1 is stopped is less than a specified pressure difference judgment threshold, the ECM 8 diagnoses that there is an abnormality in the first passage 32 of the blow-by gas recirculation system 31.

[0084] In the second embodiment, when the internal combustion engine 1 is driven by the electric motor, the pressure change (relative to the normal pressure change) caused by the abnormality of the first passage 32 is stable. Therefore, the abnormality of the first passage 32 (blow-by gas return passage) can be diagnosed based on the pressure of the intake passage 3.

[0085] Pressure sensor 53 is not designed for diagnosing malfunctions in the first passage 32 (bleed gas return passage), and existing sensors that detect intake pressure within the intake manifold 2 can be used.

[0086] If the pressure of the intake passage 3 is set as the diagnostic parameter for diagnosing the abnormality of the first passage 32, the abnormality diagnosis of the gas backflow system 31 can be performed using a general intake pressure sensor, i.e., pressure sensor 53, without the need for additional sensors.

[0087] The specific embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments and various modifications can be made without departing from its spirit.

[0088] For example, in the first and second embodiments described above, the one-way valve 35 of the first passage 32 can also be omitted.

[0089] For example, when diagnosing anomalies in the gas return system 31, it is possible to perform the diagnosis without converting (correcting) the average intake pressure when the motor is running and the average intake pressure when it is stopped to the values ​​of the standard environmental conditions.

[0090] For example, as long as the internal combustion engine 1 can be driven by an electric motor, the abnormal diagnosis of the blow-by gas recirculation system 31 in the above embodiments can also be applied to vehicles other than series hybrid vehicles.

[0091] For example, the abnormal diagnosis of the blow-by gas recirculation system 31 in the first embodiment described above can also be determined by the following condition: if the intake pressure during motor operation or the average intake pressure during motor operation exceeds a predetermined pressure threshold, it can be determined that the third passage 34 of the blow-by gas recirculation system 31 is abnormal. For example, if the third passage 34 of the blow-by gas recirculation system 31 becomes detached, even if the throttle valve 6 is closed, air will still flow in from the downstream side of the throttle valve 6. Even during motor operation, the negative pressure development in the intake manifold 2 is weak, and the pressure cannot be completely reduced. Therefore, the ECM 8 can also determine that the third passage 34 of the blow-by gas recirculation system 31 is abnormal if the intake pressure during motor operation or the average intake pressure during motor operation exceeds a predetermined pressure threshold. The pressure threshold is, for example, set to a value that takes into account various fluctuations and is greater than the intake pressure during motor operation or the average intake pressure during motor operation when the third passage 34 is abnormal. Alternatively, in this case, correction can be performed by making the pressure judgment threshold smaller as the elevation increases, or by making the intake pressure during motor drive or the average intake pressure during motor drive greater as the elevation increases.

[0092] The above embodiments relate to vehicle diagnostic methods and vehicle diagnostic devices.

Claims

1. A method for diagnosing anomalies in a vehicle, the vehicle having: internal combustion engine; The first intake throttle valve is disposed in the intake passage of the aforementioned internal combustion engine to control the amount of air drawn into the aforementioned internal combustion engine. The fresh air inlet passage is connected to the intake passage upstream of the first intake throttle valve and can introduce fresh air into the crankcase. A gas return path for bypass gas, connected to the intake passage downstream of the aforementioned first intake throttle valve, is used to guide bypass gas into the intake passage; and A pressure sensor is provided, which is capable of detecting the intake pressure in the intake passage downstream of the first intake throttle valve. In the diagnostic methods for this vehicle, When the internal combustion engine is driven by an electric motor with the first intake throttle valve reduced to a specified opening, the intake pressure detected by the pressure sensor during motor drive is used to diagnose whether there is any abnormality in the blow-by gas return path.

2. The vehicle anomaly diagnosis method according to claim 1, wherein, In the aforementioned fresh air inlet passage, there is no control valve on the passage that can adjust the flow of fresh air.

3. The vehicle anomaly diagnosis method according to claim 2, wherein, If the pressure difference between the intake pressure when the engine is stopped and the intake pressure when the engine is driven by the motor, i.e., the first pressure value, is less than the specified pressure difference judgment threshold, it is diagnosed that there is an abnormality in the gas return path of the blow-by gas. The intake pressure when the engine is stopped is detected by the pressure sensor when the engine has stopped.

4. The vehicle anomaly diagnosis method according to claim 3, wherein, The differential pressure threshold is corrected in such a way that the differential pressure threshold is smaller when the elevation is higher than when the elevation is lower, or the first pressure value is corrected in such a way that the first pressure value is larger when the elevation is higher than when the elevation is lower, so as to diagnose whether there is any abnormality in the gas return path.

5. The vehicle anomaly diagnosis method according to claim 2, wherein, If the intake pressure exceeds the specified pressure threshold when the motor is driven, it is diagnosed that there is an abnormality in the gas return path.

6. The vehicle anomaly diagnosis method according to claim 5, wherein, The pressure judgment threshold is corrected in a way that makes the pressure judgment threshold smaller when the elevation is higher than when the elevation is low, or the intake pressure when the motor is driven is corrected in a way that makes the intake pressure greater when the motor is driven than when the elevation is low, so as to diagnose whether there is any abnormality in the above-mentioned gas return path.

7. The vehicle anomaly diagnosis method according to claim 1, wherein, The system includes a throttle valve configured in the intake passage, a second intake throttle valve located upstream of the throttle valve, a first passage capable of introducing fresh air into the crankcase from the upstream side of the second intake throttle valve, a second passage capable of introducing blow-by gas into the intake passage at a position between the throttle valve and the second intake throttle valve, a third passage capable of introducing blow-by gas into the intake passage at a position downstream of the second intake throttle valve, and a blow-by gas control valve for controlling the flow of blow-by gas in the third passage. The first intake throttle valve mentioned above is the aforementioned throttle valve, and the aforementioned gas return path is the aforementioned third passage.

8. The vehicle anomaly diagnosis method according to claim 1, wherein, It has a throttle valve configured in the above-mentioned intake passage. The aforementioned fresh air introduction passage can introduce fresh air into the aforementioned crankcase from the upstream side of the aforementioned throttle valve. The aforementioned gas return path can guide the gas that has leaked into the intake passage at a position downstream of the aforementioned throttle valve. The first intake throttle valve mentioned above is the aforementioned throttle valve.

9. The vehicle anomaly diagnosis method according to claim 1, wherein, It has a throttle valve configured in the above-mentioned intake passage and a pressure control valve located upstream of the throttle valve. The aforementioned fresh air introduction passage can introduce fresh air into the aforementioned crankcase from the upstream side of the aforementioned pressure control valve. The aforementioned gas return path can guide the gas that has leaked into the intake passage at the position between the aforementioned throttle valve and the aforementioned pressure control valve. The first intake throttle valve mentioned above is the pressure control valve mentioned above.

10. A vehicle anomaly diagnostic device, comprising: internal combustion engine; The first intake throttle valve is disposed in the intake passage of the aforementioned internal combustion engine to control the amount of air drawn into the aforementioned internal combustion engine. The fresh air inlet passage is connected to the intake passage upstream of the first intake throttle valve and can introduce fresh air into the crankcase. The gas return path is connected to the intake passage on the downstream side of the first intake throttle valve, and can guide the gas back into the intake passage. A pressure sensor capable of detecting the intake pressure in the intake passage downstream of the first intake throttle valve; and The diagnostic unit, when the internal combustion engine is driven by an electric motor with the first intake throttle valve reduced to a specified opening, diagnoses whether there is any abnormality in the blow-by gas return path based on the intake pressure detected by the pressure sensor during motor drive.

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