Vehicle

Abstract

The present invention relates to a vehicle comprising: an engine; a turbocharger for boosting intake air to the engine; an exhaust passage connected to the engine, wherein a turbine of the turbocharger is disposed in the exhaust passage; a bypass passage bypassing the turbine and connected to the exhaust passage; an exhaust gas bypass valve for opening and closing the bypass passage; and an anomaly determination device configured to include a determination unit configured to determine an anomaly of the exhaust gas bypass valve when the engine is in a boosted operating state.

Description

Technical Field

[0001] This invention relates to a vehicle. Background Technology

[0002] A technique for determining an exhaust bypass valve malfunction when the engine is operating at low speed and low load is known (see, for example, Japanese Patent Application Publication No. 2007-056843).

[0003] Depending on the driver's driving characteristics and vehicle type, the period during which the engine operates at low speed and low load is short or its frequency is reduced, so the frequency of detecting abnormalities in the exhaust bypass valve may be reduced. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a vehicle that ensures the frequency of abnormal detection of the exhaust bypass valve.

[0005] The above objective is achieved by a vehicle comprising: an engine; a turbocharger for boosting intake air to the engine; an exhaust passage connected to the engine, wherein a turbine of the turbocharger is disposed in the exhaust passage; a bypass passage bypassing the turbine and connected to the exhaust passage; an exhaust bypass valve for opening and closing the bypass passage; and an anomaly determination device configured to include a determination unit configured to determine an anomaly of the exhaust bypass valve when the engine is in a boosted operating state.

[0006] The anomaly determination device may include an acquisition unit configured to acquire the boost pressure and intake air volume of the engine, and the determination unit may be configured to determine the anomaly of the exhaust bypass valve based on the boost pressure and intake air volume under the boost state.

[0007] The determination unit can be configured to determine the abnormality of the exhaust bypass valve based on the boost pressure and intake volume in the boost state and the boost pressure and intake volume in the idle state of the operating state.

[0008] The determination unit can be configured to determine that the waste gas bypass valve is normal when the determination value obtained by dividing the difference between the boost pressure between the idle state and the boost state by the difference between the intake air volume between the idle state and the boost state is less than a threshold, and is configured to determine that the waste gas bypass valve is abnormal when the determination value is greater than or equal to the threshold.

[0009] The determination unit can be configured to determine the abnormality of the exhaust bypass valve based on the boost pressure and intake volume in the idle state and the boost pressure and intake volume in the natural aspiration state when the operating state is not the idle state.

[0010] The pressurization state can be the full-load state with the accelerator opening at its maximum.

[0011] Effects of the present invention

[0012] According to the present invention, a vehicle is provided that can ensure the frequency of abnormal detection of the exhaust bypass valve. Attached Figure Description

[0013] Figure 1 It is a schematic structural diagram of the vehicle;

[0014] Figure 2 This is a timing diagram illustrating an example of anomaly detection control when a vehicle starts traveling at low speed from a temporary stop.

[0015] Figure 3 It is a graph showing the relationship between boost pressure and intake air volume;

[0016] Figure 4 This is a timing diagram illustrating an example of anomaly detection control when a vehicle starts traveling at high speed from a temporary stop.

[0017] Figure 5 It is a graph showing the relationship between boost pressure and intake air volume; and

[0018] Figure 6 This is a flowchart illustrating an example of anomaly detection control performed by an ECU. Detailed Implementation

[0019] [Schematic diagram of a vehicle]

[0020] Figure 1 This is a schematic structural diagram of vehicle 100. Vehicle 100 is equipped with an engine 1, an intake passage 3, an exhaust passage 4, a turbocharger 5, an intercooler 6, a catalyst 7, a bypass passage 8, an exhaust bypass valve 9, a transmission 21, a differential 23, wheels 25, and an electronic control unit (ECU) 30. Engine 1 is a multi-cylinder engine with four in-line cylinders 2, and it is a gasoline engine. However, the number of cylinders is not limited to this, and the engine can also be a diesel engine. The driving force of engine 1 is transmitted to wheels 25 via transmission 21 and differential 23.

[0021] Intake passage 3 and exhaust passage 4 are connected to engine 1. The compressor 5b of turbocharger 5 is disposed in intake passage 3. The turbine 5a of turbocharger 5 is disposed in exhaust passage 4. Turbine 5a and compressor 5b are coaxially connected via a shaft. Turbocharger 5 pressurizes the intake air flowing into engine 1.

[0022] Exhaust passage 4 is provided with a bypass passage 8 that bypasses turbine 5a and an exhaust gas bypass valve 9 for opening and closing the bypass passage 8. The exhaust gas bypass valve 9 is connected to a diaphragm-type negative pressure actuator 9a, and the ECU 30 controls the opening degree of the exhaust gas bypass valve 9 by controlling the negative pressure actuator 9a. Adjusting the opening degree of the exhaust gas bypass valve 9 regulates the distribution ratio between the exhaust flow rate through the bypass passage 8 and the exhaust flow rate through turbine 5a. This regulates the rotational driving force of turbine 5a and the amount of air compressed by compressor 5b, which regulates the boost pressure of engine 1. Specifically, regarding the distribution ratio, as the opening degree of exhaust gas bypass valve 9 decreases, the exhaust flow rate through bypass passage 8 decreases and the exhaust flow rate through turbine 5a increases. When exhaust gas bypass valve 9 is fully open, engine 1 operates in the same manner as a naturally aspirated engine without turbocharger 5. Instead of negative pressure actuator 9a, an electric actuator for electrically operating exhaust gas bypass valve 9 can be used.

[0023] An intercooler 6 is located downstream of the compressor 5b in the intake passage 3. Coolant supplied to the engine 1 flows through the intercooler 6. This causes heat exchange between the coolant flowing through the intercooler 6 and the air flowing through the intercooler 6 that cools the intake air. A throttle valve 3a is located downstream of the intercooler 6 in the intake passage 3. The intake air volume of the engine 1 is adjusted by regulating the opening of the throttle valve 3a. The ECU 30 controls the opening of the throttle valve 3a based on the accelerator opening.

[0024] A catalyst 7 for purifying exhaust gas is installed downstream of turbine 5a in exhaust passage 4. An air-fuel ratio sensor 14 is installed upstream of catalyst 7 in exhaust passage 4. An oxygen sensor 15 for detecting oxygen concentration in exhaust gas is installed downstream of catalyst 7 in exhaust passage 4.

[0025] ECU 30 includes a central processing unit (CPU), read-only memory (ROM), and random access memory (RAM). ECU 30 executes the anomaly determination control, described later, based on information from sensors, control information pre-stored in the ROM, and other data according to a control program stored in the ROM. ECU 30 is an example of an anomaly determination device. The anomaly determination control is performed by a determination unit and an acquisition unit functionally implemented via the CPU, ROM, and RAM. Details will be described later.

[0026] The ECU 30 controls the operation of the engine 1 based on detection signals from various sensors, such as the crank angle sensor 11, the air flow meter 12, the boost pressure sensor 13, the air-fuel ratio sensor 14, the oxygen sensor 15, and the accelerator pedal opening sensor 16. The crank angle sensor 11 detects the rotation angle of the crankshaft of the engine 1. The air flow meter 12 detects the amount of air intake in the intake passage 3. The boost pressure sensor 13 detects the pressure in the intake passage 3 downstream of the compressor 5b and upstream of the throttle valve 3a. The air-fuel ratio sensor 14 detects the air-fuel ratio of the exhaust gas flowing into the catalyst 7. The oxygen sensor 15 detects the oxygen concentration in the exhaust gas exiting the catalyst 7. The accelerator pedal opening sensor 16 detects the opening degree of the accelerator pedal operated by the driver.

[0027] ECU 30 outputs an indicated negative pressure value to the negative pressure actuator 9a, causing the exhaust gas bypass valve 9 to open according to the operating state of engine 1. The indicated negative pressure value refers to the indicated value of the negative pressure in the negative pressure chamber of the diaphragm-type negative pressure actuator 9a. In this embodiment, the indicated negative pressure value is an absolute value relative to atmospheric pressure and is expressed as a positive value. Here, as the pressure in the negative pressure chamber decreases from atmospheric pressure, the opening degree of the exhaust gas bypass valve 9 decreases, and as the pressure in the negative pressure chamber increases to atmospheric pressure, the opening degree of the exhaust gas bypass valve 9 increases. That is, as the required opening degree of the exhaust gas bypass valve 9 increases, the indicated negative pressure value is adjusted to a smaller value, and as the required opening degree of the exhaust gas bypass valve 9 decreases, the indicated negative pressure value is adjusted to a larger value. For example, when the required opening degree of the exhaust gas bypass valve 9 is at its maximum, as described later, the indicated negative pressure value is controlled to be less than the pressure value n1. The required opening degree of the exhaust gas bypass valve 9 is at its maximum when the engine 1 is in idle or naturally aspirated state. When engine 1 is in boost mode, the required opening degree of exhaust bypass valve 9 is not at its maximum.

[0028] As described above, when the exhaust bypass valve 9 is in its normal state, its opening is controlled according to the indicated negative pressure value output from the ECU 30 to the negative pressure actuator 9a, which controls the boost pressure. However, an abnormal state may occur where the exhaust bypass valve 9 is stuck in a fully closed state (hereinafter referred to as a stuck-closed state). In this case, since the opening of the exhaust bypass valve 9 remains fully closed regardless of the indicated negative pressure value of the negative pressure actuator 9a, driving performance may be affected. Therefore, the ECU 30 performs abnormal determination control to determine this stuck-closed state of the exhaust bypass valve 9.

[0029] [Abnormal Detection and Control]

[0030] Figure 2 This is a timing diagram illustrating an example of anomaly detection control when vehicle 100 starts moving at low speed from a temporarily stopped state. Figure 2The changes in intake air volume, vehicle speed, boost pressure, and indicated negative pressure value are shown. When the first monitoring condition is met during the temporary stop of vehicle 100 (time t1), ECU 30 obtains the intake air volume I1 and boost pressure P1 (time t2). The first monitoring condition is when the intake air volume is less than the air volume g1 and the indicated negative pressure value is less than the negative pressure value n1. An indicated negative pressure value less than pressure value n1 indicates that the required opening degree of the exhaust bypass valve 9 is maximum. In other words, the first monitoring condition indicates that the engine 1 is operating at idle speed.

[0031] Next, the driver operates the accelerator opening to a relatively small position, temporarily increasing the indicated negative pressure value of the negative pressure actuator 9a and decreasing the required opening of the exhaust bypass valve 9. As a result, the intake air volume and boost pressure increase, and the vehicle accelerates to 100 km / h (time t3). Afterward, the indicated negative pressure value drops again to below the pressure value n1, and the required opening of the exhaust bypass valve 9 is at its maximum. Thus, the vehicle speed is maintained at a low speed (time t4), thereby stabilizing the intake air volume and boost pressure.

[0032] Next, when the second monitoring condition is met (time t5), ECU 30 obtains the intake air volume I2 and boost pressure P2 (time t6). The second monitoring condition is condition (a) where the intake air volume is greater than the air volume g2 and the indicated negative pressure value is less than the negative pressure value n1. Similarly, in this case, an indicated negative pressure value less than n1 indicates that the required opening degree of the exhaust bypass valve 9 is at its maximum. In other words, condition (a) indicates that the engine 1 is operating in a naturally aspirated state other than idle.

[0033] Here, under normal conditions, the required opening degree of the wastegate valve 9 temporarily becomes zero during acceleration, then returns to its maximum after the vehicle speed stabilizes, and the boost pressure decreases. Therefore, the boost pressure P2 is approximately the same as the boost pressure P1. However, when the wastegate valve 9 is locked shut, the exhaust gas from engine 1 passes through turbine 5a instead of bypass passage 8, and even after the vehicle speed stabilizes, the boost pressure does not decrease but remains high. Therefore, as... Figure 2 As shown, the boost pressure P2x under abnormal conditions at time t6 is higher than the boost pressure P2 under normal conditions.

[0034] ECU 30 and below performs anomaly detection as follows: The difference between the boost pressure obtained when the first and second monitoring conditions are met is divided by the difference between the intake air volume obtained when the first and second monitoring conditions are met. This calculated value is called the judgment value. Therefore, in Figure 2 Under normal conditions, the judgment value = (P2-P1) / (I2-I1) is valid. Figure 2 Under the abnormal state of the waste gas bypass valve 9 shown, the judgment value = (P2x-P1) / (I2-I1) is valid.

[0035] Figure 3 It is a graph showing the relationship between the boost pressure and the intake air amount. The vertical axis represents the boost pressure, and the horizontal axis represents the intake air amount. The determination value corresponds to Figure 3 the slope of the line segment in the graph of

[0036] Thus, when the vehicle 100 starts low-speed driving from the temporary stop state, the above-described abnormality determination control is executed. However, for example, when the vehicle 100 is a sports car and the driver frequently steps on the accelerator forcefully, the frequency of low-speed driving as described above may decrease, so that the execution frequency of the abnormality determination control may decrease. Therefore, the ECU 30 in the present embodiment executes the abnormality determination control even when the vehicle 100 starts high-speed driving from the temporary stop state, as described below.

[0037] Figure 4 It is a timing chart showing an example of the abnormality determination control when the vehicle 100 starts high-speed driving from the temporary stop state. Figure 4 Corresponding to Figure 2 . When the first monitoring condition is satisfied (time t1), the ECU 30 obtains the intake air amount I1 and the boost pressure P1 (time t2). Next, the driver operates the accelerator to fully open it, and the intake air amount and the boost pressure increase, so the vehicle 100 accelerates (time t3). After that, the vehicle maintains a high speed (time t4), and the indicated negative pressure value is controlled to be greater than the value n1 to stabilize the intake air amount and the boost pressure.

[0038] After that, when the second monitoring condition is satisfied (time t5), the ECU 30 obtains the intake air amount I3 and the boost pressure P3 (time t6). The second monitoring condition is condition (b) where the intake air amount and the boost pressure are stable, the intake air amount is greater than the air amount g3 and less than the air amount g4, and the indicated negative pressure value is less than the pressure value n2. The indicated negative pressure value less than the value n2 indicates a case where the required opening degree of the wastegate valve 9 is not zero. In other words, condition (b) indicates that the operating state of the engine 1 is a boosted state. The boosted state required by condition (b) is a full-load state where the accelerator opening degree is maximum and the required opening degree of the throttle valve 3a is maximum. Therefore, when any one of the above conditions (a) and (b) is satisfied, it is considered that the second monitoring condition is satisfied. Regarding the intake air amount, the relationship g2 < g3 < g4 holds. Regarding the indicated negative pressure value, the relationship air pressure = 0 < n1 < n2 holds.

[0039] Here, when the wastegate valve 9 is functioning normally, the required opening degree of the wastegate valve 9 is maintained, causing it to partially open during acceleration, thus increasing the boost pressure and maintaining it at a predetermined value. However, when the wastegate valve 9 is stuck closed, all exhaust from engine 1 passes through turbine 5a, resulting in a significant increase in boost pressure. Therefore, as... Figure 4 As shown, the boost pressure P3x under the abnormal state at time t6 is higher than the boost pressure P3 under the normal state. Therefore, in Figure 4 Under normal conditions, the judgment value = (P3-P1) / (I3-I1) is valid for the waste gas bypass valve 9 shown. Figure 4 Under the abnormal state of the waste gas bypass valve 9 shown, the judgment value = (P3x-P1) / (I3-I1) is valid.

[0040] Figure 5 It is a graph showing the relationship between boost pressure and intake air volume. Figure 5 Corresponding to Figure 3 When the judgment value is less than the threshold T2, it is judged as a normal state. When the judgment value is equal to or greater than the threshold T2, it is judged as an abnormal state. Threshold T2 is greater than... Figure 3 The threshold T1 is shown.

[0041] Thus, since condition (b) is included in the second monitoring condition, the frequency of execution of the anomaly determination control can be ensured even when the frequency of low-speed driving is low.

[0042] For example, when the second monitoring condition only includes condition (a), considering safety, it is conceivable to restrict the transition to a boost state until the normal state of the exhaust bypass valve 9 is determined. In this case, driving performance deteriorates until the second monitoring condition is met. Since condition (b) is included in the second monitoring condition as described above, anomaly determination can be performed even in a boost state. Therefore, the aforementioned restriction is unnecessary, and the deterioration of driving performance can be suppressed.

[0043] As described above, in condition (b), the intake air volume is limited to be greater than air volume g3 and less than air volume g4. This intake air volume range is set to be the range where the difference between the boost pressure under normal conditions and the boost pressure under fully closed and locked conditions is large. That is, when the intake air volume falls within this range, the difference between the boost pressure under normal conditions and the boost pressure under locked and closed conditions is large. Therefore, anomaly detection can be performed accurately.

[0044] Figure 6This is a flowchart illustrating an example of anomaly detection control performed by ECU 30. ECU 30 determines whether a first monitoring condition is met (step S1). If not in step S1, the control ends. If yes in step S1, ECU 30 obtains the boost pressure and intake air volume based on the detection values ​​of boost pressure sensor 13 and air flow meter 12 (step S2). Step S2 is an example of a process performed by the acquisition unit.

[0045] Next, ECU 30 determines whether the second monitoring condition is met (step S3). As described above, the second monitoring condition is considered met when either condition (a) or (b) is met. If step S3 is "No", the control ends. If step S3 is "Yes", ECU 30 obtains the boost pressure and intake air volume (step S4). Step S4 is an example of the process performed by the acquisition unit. Next, ECU 30 calculates the determination value based on the turbo boost pressure and intake air volume obtained in steps S2 and S4 using the method described above (step S5).

[0046] Next, ECU 30 determines whether the determined value is less than a threshold (step S6). As described above, threshold T1 is used when condition (a) in the second monitoring condition is met. Threshold T2 is used when condition (b) in the second monitoring condition is met. Threshold T1 is the lower limit of the boost pressure difference relative to the intake air volume difference when the exhaust bypass valve 9 is locked after switching from idle to naturally aspirated state. Threshold T2 is the lower limit of the boost pressure difference relative to the intake air volume difference when the exhaust bypass valve 9 is locked after switching from idle to boosted state. Threshold T2 is not limited to a fixed value and can be variably set according to the intake air volume.

[0047] If the condition is "Yes" in step S6, the ECU 30 determines that the exhaust gas bypass valve 9 is in a normal state (step S7). If the condition is "No" in step S6, the ECU 30 determines that the exhaust gas bypass valve 9 is in an abnormal state of being stuck closed (step S8). Steps S7 and S8 are examples of the processing performed by the determination unit. When an abnormality determination is made, the ECU 30 can notify the driver, for example, by turning on the malfunction indicator lamp (MIL) that an abnormality has occurred in the exhaust gas bypass valve 9.

[0048] In the above embodiments, anomaly determination is performed based on the boost pressure and intake air volume in both the idle and boost states. For example, when the value obtained by dividing the boost pressure by the intake air volume in the boost state is less than a predetermined threshold, the waste gas bypass valve 9 can be determined to be normal. When the value is equal to or greater than the threshold, the waste gas bypass valve 9 is determined to be abnormal.

[0049] In the above embodiments, the full-load state has been described as an example of a pressurization state in which condition (b) of the second monitoring condition is met, but the invention is not limited thereto. For example, the pressurization state may be a case where the accelerator opening is equal to or greater than a predetermined opening.

[0050] Vehicle 100 is an engine vehicle that is only equipped with engine 1 as a drive source, but it is not limited to this. It can also be a hybrid vehicle that is equipped with an electric motor as a drive source in addition to an engine.

[0051] Although some embodiments of the present invention have been described in detail, the present invention is not limited to the specific embodiments, but can be modified or changed within the scope of the claimed invention.

Claims

1. A vehicle comprising: engine; A turbocharger that provides air intake boost to the engine; An exhaust passage connected to the engine, wherein the turbine of the turbocharger is disposed in the exhaust passage; A bypass passage that bypasses the turbine and connects to the exhaust passage; Open and close the exhaust gas bypass valve of the bypass passage; and An anomaly determination device is configured to include a determination unit, wherein the determination unit is configured to determine an anomaly of the exhaust bypass valve when the engine is in a boosted operating state. The anomaly detection device includes an acquisition unit configured to acquire the boost pressure and intake air volume of the engine. The determination unit is configured to determine the abnormality of the exhaust bypass valve based on the boost pressure and intake air volume under the boost state. The determination unit is configured to determine the abnormality of the exhaust bypass valve based on the boost pressure and intake volume in the boost state and the boost pressure and intake volume in the idle state of the operating state.

2. The vehicle according to claim 1, wherein, The determination unit is configured to determine that the waste gas bypass valve is normal when the determination value obtained by dividing the difference between the boost pressure between the idle state and the boost state by the difference between the intake air volume between the idle state and the boost state is less than a threshold, and is configured to determine that the waste gas bypass valve is abnormal when the determination value is greater than or equal to the threshold.

3. The vehicle according to claim 1 or 2, wherein, The determination unit is configured to determine the abnormality of the exhaust bypass valve based on the boost pressure and intake volume in the idle state and the boost pressure and intake volume in the natural aspiration state when the operating state is not the idle state.

4. The vehicle according to claim 1 or 2, wherein, The pressurization state is the full-load state with the accelerator at its maximum opening.

Images