Abstract: An engine ECU executes a program including a step of, when an absolute value of a difference between a determination value V(KX) used for determining presence or absence of knocking and a maximum value V(MAX) of magnitude value LOG(V), which is obtained by logarithmically converting a magnitude V detected based on a signal sent from a knock sensor, is greater than the product of a standard deviation ? and a coefficient U(3) in a frequency distribution of magnitude values LOG(V) for N cycle(s), setting a value obtained by adding the product of the standard deviation ? and the coefficient U(3) to the maximum value V(MAX) of the magnitude value LOG(V) as the determination value V(KX).

Abstract: An engine ECU executes a program including the steps of: calculating a correlation coefficient K based on the result of comparing a vibration waveform of an engine and a knock waveform model stored previously; calculating a magnitude value LOG(V) from the magnitude V detected based on a signal transmitted from a knock sensor; creating frequency distribution of magnitude values LOG(V) by using magnitude values LOG(V) in an ignition cycle in which the correlation coefficient K larger than a threshold K(1) is calculated; and counting knock proportion KC by using the created frequency distribution. If the vibration waveform includes a waveform of vibration of noise components, the correlation coefficient K is calculated to be smaller comparing with a case of not including it.

Abstract: An engine ECU executes a program including a step of calculating a knock intensity N as based on comparing a waveform detected as a waveform of a vibration attributed to knocking with a knock waveform model stored in a memory as a waveform of a vibration attributed to knocking for crank angles except for crank angles where a magnitude of a vibration not attributed to knocking is greater than a predetermined magnitude, a step of determining that the engine knocks if knock intensity N is larger than a predetermined reference value, and a step of determining that the engine does not knock if knock intensity N is not larger than a predetermined reference value.

Abstract: An engine ECU includes a bandpass filter (1) extracting only vibrations at a first frequency band A, a bandpass filter (2) extracting only vibrations at a second frequency band B, a bandpass filter (3) extracting only vibrations at a third frequency band C, and a bandpass filter (4) extracting only vibrations at a fourth frequency band D including the first to third frequency bands A-C. The engine ECU determines whether knocking occurred or not based on a vibration waveform of the fourth frequency band D and a peak value in magnitude of vibrations in a synthesized waveform of the first to third frequency bands.

Abstract: An engine adjusts the amount of intake air by cooperative control for the valve duration of the intake valve and the opening degree of the throttle valve. In the engine, the valve duration is fixed to a warm-up valve duration ?w in a low-to-middle speed range of the engine during a period from immediately after starting of the engine to when warm-up is completed. In a high speed range, on the other hand, the valve duration is increased from the warm-up valve duration ?w in accordance with increase in the engine speed Ne.

Abstract: A working angle (lift amount) of an intake valve is set to a predetermined first set value A1 during a period from when starting of the engine is initiated until when the engine is shifted to an initial combustion state, and the working angle is changed to a second set value A2 (=previous value (initial value is A1)+?) that is larger than the first set value A1 during a period from when the engine is shifted to the initial combustion state until when the engine is shifted to a perfect combustion state. When an engine rotational speed becomes equal to or higher than a reference rotational speed n1, it is determined that the engine has been shifted to the perfect combustion state, after which an engine starting routine ends.

Abstract: An engine ECU 200 includes a bandpass filter (1), a bandpass filter (2), and a bandpass filter (3). The bandpass filter (1) extracts only vibrations at a first frequency band A from the vibrations detected by a knock sensor. The bandpass filter (2) extracts only vibrations at a second frequency band B from the vibrations detected by the knock sensor. The bandpass filter (3) extracts only vibrations at a third frequency band C from the vibrations detected by the knock sensor. The first to third frequency bands A-C are identical in bandwidth. The engine ECU calculates a peak value in magnitude of vibrations in a synthesized waveform of these frequency bands, and determines whether knocking occurred or not based on the peak value.

Abstract: An engine ECU executes a program including the steps of: comparing a vibration waveform of an engine and a knock waveform model stored in advance to calculate a correlation coefficient K; prohibiting correction when a correction prohibiting condition of a determination value V(KX) is satisfied, the determination value V(KX) compared with a knock magnitude N calculated from the correlation coefficient K so as to control the ignition timing; and correcting the determination value V(KX) based on a magnitude value LOG(V) calculated from a magnitude V of vibration in an ignition cycle in which the correlation coefficient K greater than a threshold value K(1) is calculated when the correction prohibiting condition of determination value V(KX) is not satisfied. The correlation coefficient K is calculated as a smaller value when the vibration waveform includes a waveform of vibration of a noise component as compared with that when the vibration waveform does not include it.

Abstract: An engine ECU executes a program including a step of calculating intensity values LOG(V), a step of detecting vibration waveforms, a step of calculating a correlation coefficient K based on vibration waveforms, a step of preparing frequency distribution of intensity values LOG(V) smaller than a threshold V(1) and intensity values LOG(V) in an ignition cycle where correlation coefficient K is larger than a threshold K(1), a step of calculating a knock determination level V(KD) based on a median V(50) and a standard deviation ? of intensity values LOG(V), and a step of counting the number of intensity values LOG(V) larger than knock determination level V(KD) as the number of times that knocking has occurred.

Abstract: A knock waveform model (thick line) is prepared by correcting a line (thin line) representing an average value of a vibration waveform measured in advance to have more moderate inclination. The knocking determination device determines whether knocking occurred in an engine or not, based on a result of comparison between the knock waveform model and a waveform detected by a knock sensor.

Abstract: An engine adjusts the amount of intake air by cooperative control for the valve duration of the intake valve and the opening degree of the throttle valve. In the engine, the valve duration is fixed to a warm-up valve duration ?w in a low-to-middle speed range of the engine during a period from immediately after starting of the engine to when warm-up is completed. In a high speed range, on the other hand, the valve duration is increased from the warm-up valve duration ?w in accordance with increase in the engine speed Ne.

Abstract: An engine ECU executes a program including a step of calculating a knock intensity N as based on comparing a waveform detected as a waveform of a vibration attributed to knocking with a knock waveform model stored in a memory as a waveform of a vibration attributed to knocking for crank angles except for crank angles where a magnitude of a vibration not attributed to knocking is greater than a predetermined magnitude, a step of determining that the engine knocks if knock intensity N is larger than a predetermined reference value, and a step of determining that the engine does not knock if knock intensity N is not larger than a predetermined reference value.

Abstract: A working angle (lift amount) of an intake valve is set to a predetermined first set value A1 during a period from when starting of the engine is initiated until when the engine is shifted to an initial combustion state, and the working angle is changed to a second set value A2 (=previous value (initial value is A1)+?) that is larger than the first set value A1 during a period from when the engine is shifted to the initial combustion state until when the engine is shifted to a perfect combustion state. When an engine rotational speed becomes equal to or higher than a reference rotational speed n1, it is determined that the engine has been shifted to the perfect combustion state, after which an engine starting routine ends.

Abstract: A malfunction determining apparatus of an exhaust gas recirculation system can prevent an erroneous determination that an exhaust gas recirculating valve is normal when the valve has a cause of malfunctioning. The exhaust gas recirculating valve is provided between an exhaust passage and an intake passage of an internal combustion engine of a vehicle. An operation determining part determines whether the exhaust gas recirculating valve has been operated at least once. A malfunction determining part performs a determination as to whether the exhaust gas recirculation system is malfunctioning. The determination is performed after the exhaust gas recirculating valve has been operated at least once.

Abstract: A malfunction determining apparatus of an exhaust gas recirculation system performs an accurate determination of malfunctioning of an EGR valve based on an amount of change in the actual degree of opening of the EGR valve. The EGR valve is provided between an exhaust passage and an intake passage of an internal combustion engine of a vehicle. An actual valve opening degree detector detects an actual valve opening degree of the EGR valve. A target valve opening degree calculator calculates a target valve opening degree of the EGR valve. A malfunction determining part calculates an amount of change in the actual valve opening degree when an amount of change in the target valve opening degree is equal to or greater than a predetermined value so as to determine an occurrence of malfunction in the exhaust gas recirculation system based on a comparison between the amount of change in the actual valve opening degree and a second predetermined value.