Anomaly determination device and anomaly determination method

An anomaly determination device for use with a turbocharger, wherein

• the turbocharger includes
• a turbine housing, which includes
• a scroll passage, in which a turbine wheel configured to be rotated by exhaust gas is housed,
• a discharge passage, which is connected to the scroll passage and in which exhaust gas from the scroll passage flows, and
• a bypass passage, which connects a section of the scroll passage upstream of the turbine wheel to the discharge passage,
• a wastegate, which abuts against a valve seat provided in the turbine housing when the bypass passage is fully closed;
• an electric actuator configured to drive the wastegate;
• a coupling mechanism, which couples the wastegate to the actuator;
• a stopper, which abuts against the wastegate or the coupling mechanism when the bypass passage is fully open to restrict a movement of the wastegate to an open position;
• a sensor, which detects a position of an output shaft of the actuator;
• a control unit, which controls energization of the actuator;
• and
• an anomaly determination unit, which determines whether an anomaly is present in the coupling mechanism based on a detection value detected by the sensor,
• the anomaly determination unit includes circuitry that is configured to execute
• a first anomaly determination process for determining that an anomaly is present in the coupling mechanism when at least one of first and second conditions is met, the first condition being that a fully-closed-time detection value is outside a closed-side normal range set in advance and the second condition being that an fully-open-time detection value is outside an open-side normal range set in advance, and
• a second anomaly determination process for determining that an anomaly is present in the coupling mechanism if a difference between the fully-closed-time detection value and the fully-open-time detection value is outside a normal distance range set in advance when it is not determined in the first anomaly determination process that an anomaly is present in the coupling mechanism,
• the fully-closed-time detection value is a detection value of the sensor when the control unit energizes the actuator to cause the wastegate to abut against the valve seat, and
• the fully-open-time detection value is a detection value of the sensor when the control unit energizes the actuator to cause the wastegate to abut against the stopper.

An anomaly determination method for a turbocharger, wherein

• the turbocharger includes
• a turbine housing, which includes
• a scroll passage, in which a turbine wheel configured to be rotated by exhaust gas is housed,
• a discharge passage, which is connected to the scroll passage and in which exhaust gas from the scroll passage flows, and
• a bypass passage, which connects a section of the scroll passage upstream of the turbine wheel to the discharge passage,
• a wastegate, which abuts against a valve seat provided in the turbine housing when the bypass passage is fully closed;
• an electric actuator configured to drive the wastegate;
• a coupling mechanism, which couples the wastegate to the actuator;
• a stopper, which abuts against the wastegate or the coupling mechanism when the bypass passage is fully open to restrict a movement of the wastegate to an open position;
• a sensor, which detects a position of an output shaft of the actuator;
• a control unit, which controls energization of the actuator;
• and
• an anomaly determination unit, which determines whether an anomaly is present in the coupling mechanism based on a detection value detected by the sensor,
• the anomaly determination method comprising:
• executing, using the anomaly determination unit, a first anomaly determination process for determining that an anomaly is present in the coupling mechanism when at least one of first and second conditions is met, the first condition being that a fully-closed-time detection value is outside a closed-side normal range set in advance and the second condition being that an fully-open-time detection value is outside an open-side normal range set in advance;
• and
• executing, using the anomaly determination unit, a second anomaly determination process for determining that an anomaly is present in the coupling mechanism if a difference between the fully-closed-time detection value and the fully-open-time detection value is outside a normal distance range set in advance when it is not determined in the first anomaly determination process that an anomaly is present in the coupling mechanism, wherein
• the fully-closed-time detection value is a detection value of the sensor when the control unit energizes the actuator to cause the wastegate to abut against the valve seat, and
• the fully-open-time detection value is a detection value of the sensor when the control unit energizes the actuator to cause the wastegate to abut against the stopper.