Abstract: An ignition timing control device includes a storage device that stores a normal signal generation model configured to output, upon receiving an output value of a knocking sensor, a noise-removed output value therefrom which an unlearned noise component value has been removed, and a first learned neural network pre-learned to output, upon receiving one of the output value of the knocking sensor and the noise-removed output value, an estimated value of a knocking intensity representative value, and a processor that acquires the estimated value by inputting the output value of the knocking sensor to the normal signal generation model and inputting the noise-removed output value to the first learned neural network, and executes retarding control of an ignition timing based on the acquired estimated value.

Abstract: An ignition timing control device includes a storage device that stores a normal signal generation model configured to output, upon receiving an output value of a knocking sensor, a noise-removed output value therefrom which an unlearned noise component value has been removed, and a first learned neural network pre-learned to output, upon receiving one of the output value of the knocking sensor and the noise-removed output value, an estimated value of a knocking intensity representative value, and a processor that acquires the estimated value by inputting the output value of the knocking sensor to the normal signal generation model and inputting the noise-removed output value to the first learned neural network, and executes retarding control of an ignition timing based on the acquired estimated value.

Abstract: There is provided a pressure detection device including: a pressure detection element which receives pressure so as to output a detection signal corresponding to the pressure P; and a processing circuit which processes and outputs the detection signal output from the pressure detection element, where the processing circuit includes: a voltage transformation circuit which only transforms a power supply voltage fed from an external power supply so as to obtain a first reference voltage with a predetermined voltage value; an integrator circuit which uses the first reference voltage as an operation reference to perform integral processing on the detection signal so as to convert the detection signal into a voltage waveform; and at least one or more amplifier circuits which use a second reference voltage with a predetermined voltage value as an operation reference to perform amplification processing on an output signal from the integrator circuit.

Abstract: A method for producing an output data stream includes picking up and digitalizing a combustion chamber signal to a combustion chamber signal data stream and, simultaneously therewith, picking up and digitalizing a crankshaft angle signal to a crankshaft signal data stream. The combustion chamber signal data stream is split or duplicated into a first and a second combustion chamber signal data flow. The first combustion chamber signal data flow is filtered to a first filtered combustion chamber signal data stream and then transformed to a first transformed combustion chamber signal data stream. The second combustion chamber signal data flow is transformed to a second transformed combustion chamber signal data stream. The first and second transformed combustion chamber signal data streams are combined to an output data stream which comprises the first and second transformed combustion chamber signal data streams in a respective first and second crankshaft angle range.

Abstract: Provided is a device for detecting a malfunction of a rotating machine, the device being able to early detect the malfunction and to have a reduced size. The device includes a detecting unit for detecting vibration of the machine, sampling a signal indicative of the vibration with a predetermined sampling frequency, and outputting, at a time at intervals of a predetermined period, a plurality of the sampled data detected within the predetermined period, a storage for storing the plurality of the sampled data, a frequency analyzer for analyzing the frequency of the plurality of the sampled data, a determination unit for performing a primary determination based on the result of the analysis, a display unit for displaying the result of the analysis in chronological order and in real time, and a communication unit for transmitting the plurality of the sampled data to an information-processing device for performing a secondary determination.

Abstract: A method and an arrangement for operating an internal combustion engine. According to the method, a load threshold is defined below which load control by a throttle valve is performed.

Abstract: Methods and systems are provided for diagnosing a knock sensor of an engine system by actively inducing knock in an engine cylinder. A laser ignition device is operated in an engine cylinder located closest to the knock sensor while the engine is at rest and with the cylinder parked with an intake valve and an exhaust valve closed to generate and trap heat in the cylinder. Spark timing is advanced in the cylinder on the subsequent restart, which in combination with the trapped heat induces knock, and elicits a response from a functional knock sensor.

Abstract: A method of deriving the health of a first cylinder in a reciprocating device includes receiving a first signal from a first knock sensor in proximity to the first cylinder, receiving a second signal from a second knock sensor in proximity to a second cylinder, processing the first signal and the second signal, and deriving the health of the first cylinder by determining whether the first signal is coherent with the second signal.

Abstract: A method of diagnosing a knock sensor includes steps of receiving data from the knock sensor, the knock sensor configured to be coupled to an engine, processing the data to derive one or more events from the data, and determining whether the one or more events took place at a known time or a known crank position.

Abstract: A method for diagnosing a variable-lift camshaft follower of an internal combustion includes detecting a first knock using a spark knock sensor of the internal combustion engine; retarding ignition timing of the internal combustion engine after detecting the first knock such that the ignition timing is retarded sufficiently to ensure that spark knock is no longer possible; detecting a second knock using the spark knock sensor after retarding the ignition timing sufficiently to ensure that spark knock is no longer possible; determining that the variable-lift camshaft follower is not functioning as desired based on the second knock; and activating a malfunction alert based on the determining that the variable-lift camshaft follower is not functioning as desired.

Abstract: A negative pressure detection part detects a negative pressure from a signal of a negative pressure sensor detecting a negative pressure generated due to rotation of an internal combustion engine. The negative pressure is used to assist a vehicle driver's braking operation. An abnormality determination part determines, during continuation of the internal combustion engine stopped state, that the negative pressure sensor is in an abnormal condition if the detected negative pressure is out of a normal range near an atmospheric pressure to a vacuum pressure side when an operation of decreasing the negative pressure is performed on a brake pedal greater than or equal to a predetermined number of times or greater than or equal to a predetermined period of time or when a total operation amount of the decreasing operation is greater than or equal to a predetermined amount.

Abstract: Computer-implemented methods, computer program products, and computer systems are described for determining cylinder health characteristic in a reciprocating piston engine of the type including a piston-cylinder assembly and a crankshaft. The piston-cylinder assembly includes a cylinder and a piston configured to translate within the cylinder as the crankshaft rotates. In one embodiment, the computer-implemented method includes rotating the crankshaft in a first direction, while generating a first data set comprising a first plurality of piston position measurements and corresponding pressure indicator measurements. The crankshaft is further rotated in a second opposing direction, while a second data set is generated comprising a second plurality of piston position measurements and corresponding pressure indicator measurements. A symmetric aspect between the first and second data sets is then identified and utilized to determining a cylinder health characteristic for the piston-cylinder assembly.

Abstract: A method detects events in an accoustic signal subject to cyclostationary background noise by first segmenting the signal into cycles. Features with a fixed dimension are derived from the cycles, such that the timing of the features is relative to a cycle time. The features are normalized using an estimate of the cyclostationary background noise. Then, after the normalizing, a classifier is applied to the features to detect the events.

Abstract: In a power tool, an internal combustion engine is coupled by a clutch to a tool member. An ignition control device is provided that for each engine speed of the internal combustion engine specifies at least one ignition timing. For each engine speed of a first engine speed range a correlated first ignition timing is specified, wherein each first ignition timing is an ignition timing of a first ignition timing range. For each engine speed of a second engine speed range, adjoining the first engine speed range, a correlated second ignition timing is specified, wherein each second ignition timing is an ignition timing of a second ignition timing range. The first ignition timing is retarded by at least 5° crank angle relative to the second ignition timing. The first engine speed range extends at least from the coupling engine speed range to the limit engine speed of approximately 7,000 RPM.

Abstract: A computer-implemented method, computer program product, and computer system is described for identifying top dead center of a reciprocating piston. A piston is progressed in a first direction along a first piston stroke included in the cyclical motion, toward an expected top dead center position of the piston. A plurality of piston positions and corresponding pressure indicators are determined during the first-direction progression of the piston. The piston is progressed in a second direction along a second piston stroke included in the cyclical motion, toward the expected top dead center position of the piston. A plurality of piston positions and corresponding pressure indicators are determined during the second-direction progression of the piston. One or more symmetric aspects of the first- and second-direction data are determined, and an updated top dead center position is determined based upon, at least in part, the symmetric aspects.

Abstract: Systems and methods for providing spark to an engine are described. In one example, engine knock limited spark timing is expressed as a straight line that is determined in response to engine knock, spark timing, and engine load. The method and system described herein may be performed without extensive engine calibration and mapping.

Abstract: Methods and systems are provided for selecting a group of cylinders for selective deactivation, in a variable displacement engine system, based at least on a regeneration state of an exhaust catalyst. The position of one or more valves and throttles may be adjusted based on the selective deactivation to reduce back-flow through the disabled cylinders while also maintaining conditions of a downstream exhaust catalyst. Pre-ignition and knock detection windows and thresholds may also be adjusted based on the deactivation to improve the efficiency of knock and pre-ignition detection.

Abstract: A knocking control system for a gas engine of the present invention, being configured to calculate a knocking occurrence ratio (SEV) which is a ratio of a cycle number of cycles in which a predetermined knocking occurs for a period of the cycles of the predetermined cycle number, to the predetermined cycle number, decide a target value of an ignition timing of the ignition device based on a deviation (?SEV) between an occurrence ratio delay calculation value (SEVAVE) obtained by performing delay calculation of the knocking occurrence ratio and a predetermined occurrence ratio target value (SEVSET), and drive the ignition device so that the ignition timing reaches a command value (IGN) decided according to the target value.

Abstract: There is provided a combustion state detecting apparatus capable of detecting combustion-state abnormality in an internal combustion engine. A comparison timing is set to be advanced in terms of the rotation angle of the crankshaft of an internal combustion engine with respect to the ending timing of an electric quantity based on an ion that occurs when ignition is performed normally through a predetermined ignition signal among the plurality of ignition signals; in the case where, as a result of the comparison between the detected ending timing of an electric quantity based on an ion and the comparison timing, the ending timing is advanced in terms of the rotation angle of the crankshaft with respect to the comparison timing, it is determined that the combustion based on ignition through the predetermined ignition signal is abnormal.

Abstract: An internal combustion engine includes a piston reciprocable within a cylinder, a phase controllable valvetrain configured to alter the effective compression ratio of the engine, and a knock sensor. A method for controlling the engine includes controlling the valvetrain to a first effective compression ratio whereat knock is detectable by the knock sensor and thereafter controlling the valvetrain to reduce the effective compression ratio to a point whereat knock is no longer detectable.

Abstract: An idle control device for an engine is provided that can prevent delay in return to a target revolution speed which may cause unpleasant vehicle vibration or lead to an engine stall.

Abstract: A method for supplying two types of fuel to an engine of a vehicle is disclosed. In one embodiment, an amount of a first fuel supplied to the engine is adjusted in response to a condition of a fuel separator. The method can improve vehicle drivability at least during some conditions.

Abstract: An engine ECU executes a program including a step of calculating intensity values LOG(V) based on signals transmitted from a knock sensor; a step of deciding a maximum value V(MAX) in frequency distribution of intensity values LOG(V) for N cycles (N is a natural number); a step of calculating a knock determination level V(KD) based on the frequency distribution; a step of, when the knock determination level V(KD) is smaller than the maximum value V(MAX), removing V(MAX) from the frequency distribution; and a step of counting the total frequency of removed maximum values V(MAX) as knock occupancy KC. Maximum values V(MAX) are removed until the knock determination level V(KD) and the maximum value V(MAX) coincide, and the knock determination level V(KD) is recalculated.

Abstract: The alcohol concentration detection value estimated or detected by the alcohol concentration sensor is corrected in accordance with intensity, frequency and the like of knocking to set the alcohol concentration detection value after the correction as the alcohol concentration for ignition timing control. Thereby, occurrence of the knocking can be prevented by changing ignition timing in accordance with the knocking state. In regard to the fuel injection control, the alcohol concentration detection value before the correction is used as the alcohol concentration for fuel injection control as it is without using the alcohol concentration detection value corrected in accordance with the knocking state. This prevents a fluctuation of the fuel injection quantity due to correcting the alcohol concentration detection value in accordance with the knocking state, leading to prevention of a torque fluctuation or combustion deterioration.

Abstract: A method for controlling spark timing in an internal combustion engine. The method includes determining, in response to a knock sensor mounted to the engine, a spark offset to the scheduled spark timing for the engine at relatively low engine speed which is applied to the scheduled spark timing at relatively high engine speeds. This offset is applied in conjunction with a time-varying spark retardation bias. The offset is removed at a rate proportional to the time varying spark retard bias. The bias increases if either a relatively large torque is demanded from the engine or the engine is at the relatively high speed and relatively high air charge condition; otherwise, the bias is decreased with time.

Abstract: The invention relates to a method for determining the energy (KNKE) of the knock of an internal combustion engine, using an analog signal supplied by a sensor fixed to the engine. The inventive method includes the following steps: a) the analog signal is shaped, b) the analog signal is converted into a sequence of digital samples, c) the signal is subjected to digital filtering, and d) the signal is adjusted and e) integrated. According to the method: i) the shaping of the analog signal includes combining the signal with a continuous component (Vcnf) adapted to render the shaped signal a positive signal or a zero signal, and ii) the digital filtering is carried out by a band-pass filter with an infinite impulse response, the transfer function thereof including a zero for the zero frequencies.

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: The present invention creates a method and an apparatus for blanking out interfering noise in connection with detecting knocking in an internal combustion engine. The following functions are performed: Forming a sensor signal integral value (KI) during a measurement time slot (MF) of the sensor signal of a knocking sensor; forming a correction value (DKI) for the sensor signal integral value (KI) corresponding to an interfering noise during the measurement time slot (MF); and subtracting the correction value (DKI) from the sensor signal integral value (KI) for forming a corrected sensor signal integral value (KI?) with the interfering noise blanked out.

Abstract: To provide a control apparatus for an internal combustion engine which can judge an abnormality regardless of one line type or two line type, and can also detect the classification of abnormality. The control apparatus includes: a knock sensor having a piezoelectric element for detecting vibrations that are generated in the internal combustion engine, and a resistor that is connected in parallel with the piezoelectric element; and an interface circuit that detects a knock in accordance with an output from the knock sensor and detects an abnormality of the knock sensor, and the interface circuit includes a bias unit that conducts biasing by pulling up and pulling down an output from the knock sensor, and detects the abnormality of the knock sensor with a direct current component of the bias unit.

Abstract: The method for knock detection includes establishing that knock is occurring in the internal combustion engine when the amplified knock signal exceeds a predetermined reference level in a predetermined manner. The reference level is determined on the basis of individual cylinders and the increase in the reference level is limited when a new reference level leaves a predetermined reference level range or the gradient of the sound increase exceeds a predetermined threshold value. For determination of the reference level range and/or the threshold for the gradient average values of the signals originating from the sound of other cylinders are considered.

Abstract: A misfire detector is provided that is accurate even in the case of a disturbance due to causes such as driving on a rough road. The misfire detector is equipped with a crankshaft revolution detector to measure the time period required for the crankshaft of an internal-combustion engine to revolve for a given angle. A signal-processor is also provided for detecting the misfiring of the internal-combustion engine by processing the time period. In one embodiment, the misfire detector has two filters having the same sensitivity to the misfire frequency, and differing in the sensitivity to frequencies adjacent to said misfire frequency. It can be determined that a misfire has occurred if the ratio or difference between the outputs of the two filters stays within a fixed range and one or both of the filters have respective outputs exceeding a threshold value.

Abstract: A method of controlling an internal combustion engine is provided, in which at least two operating states are differentiated, at least one operating variable of the engine being controlled, a setpoint torque being predetermined on the basis of the optimum operating point for the respective operating state and on the basis of the position of a throttle valve operated by the driver, and the value of at least one operating variable to be output being determined from the setpoint torque. A cylinder-individual firing angle retardation value is predetermined by a knock control system, so that the cylinder-individual firing angle retardation value is taken into account directly in calculating the setpoint torque.

Abstract: A device for controlling the ignition timing for internal combustion engines correctly detecting fault of a knocking sensor over the whole rotational range of the engine. The device for controlling the ignition timing takes out knocking signals and produces an ignition timing control signal relying upon the knocking signals, and comprises a knocking sensor 1, a microcomputer 2 for producing a fault detection execution signal for executing the detection of fault of the knocking sensor and for applying a pulse voltage to the knocking sensor 1 relying upon the fault detection execution signal, comparison means 5 and 6 for comparing the charging voltage or discharging voltage of the knocking sensor 1 with two different threshold values, and logic means (NOR circuit) 7 for obtaining an OR of the outputs of the comparison means 5 and 6.

Abstract: A method of operating a knock detection system of a multi-cylinder piston engine in which the knock detection system comprises a sensor arranged in connection with each cylinder and a measurement circuit connected to the sensor includes running the engine at a load being less than full load and setting the output signal of each separate sensor between certain preset limits by adjusting one or more adjustment variables of the measurement circuit. The values of the adjustment variables for each separate cylinder are stored in the detection system. During normal use, the engine is run and the previously stored values of the adjustment values for each cylinder are used in the knock detection system.

Abstract: A knocking control apparatus for a variable cylinder internal combustion engine avoids erroneous determination of knocking during a fault in a cylinder pausing mechanism to appropriately control knocking associated with the ignition timing, thereby preventing engine stall and reducing a deterioration in a catalyst. The variable cylinder internal combustion engine can be switched between a full cylinder operation mode in which all of a plurality of cylinders are operated, and a partial cylinder operation mode in which part of the plurality of cylinders is paused by a cylinder pausing mechanism.

Abstract: Method for processing a sensor signal of a knocking sensor for an internal combustion engine, having the following steps: a time window is defined for the evaluation of the sensor signal as a function of the operating state and/or the operating behavior of the internal combustion engine, a plurality of sampled values of the sensor signal are sampled within the predefined time window with a predefined sampling frequency, and an output signal which represents the knocking behavior of the internal combustion engine is determined from the sampled values, the Fourier transform of the sampled values being calculated in order to determine the output signal.

Abstract: A device having a monitoring circuit for a knock control and a control circuit which initiates substitute measures in the event of a fault in the knock control, depending on the output signal of the monitoring circuit, is described. The control unit is designed, for example, so that the number of fuel injection operations per operating cycle of a cylinder of the engine is increased as the substitute measure.

Abstract: A method for controlling knocking in multi-cylinder internal combustion engines in KC emergency operation and at activated guide-cylinder function are provided by which a torque loss is able to be avoided at low application expenditure and the functionality desired by the guide-cylinder function is maintained even in KC emergency operation. In KC emergency operation and when the guide-cylinder function is activated, cylinder pairs are formed from the cylinders operating in each case at a 360° offset. Each twin pair having at least one cylinder to be guided is assigned at least one of the available guide cylinders, so that the ignition timing retard of the cylinder pair to be guided is based on the ignition timing retard of the associated guide cylinder. Only when the number of available guide cylinders is insufficient will a safety retard timing be triggered, in which an ignition angle is adjusted which has been predefined for all cylinders.

Abstract: A method for knock control of an internal combustion engine, a knock detection being carried out on the cylinders of the internal combustion engine and a moment of ignition being retarded by a specifiable value as a function of detected knocking combustion in at least one of the cylinders, the system including at least two evaluation electronics and at least one cylinder being assigned to each of these evaluation electronics, and the knock sensor signals assigned to the cylinders being evaluated by the evaluation electronics assigned in each case, and the knock detection and the specification of the moment of ignition being effected by a control electronics, and the evaluation electronics being monitored for functionality. It is provided that, upon detection of a malfunction of at least one of the evaluation electronics, the at least one cylinder assigned to this evaluation electronics is linked to the control of at least one cylinder having intact evaluation electronics.

Abstract: A method and a device for operating an internal combustion engine are provided, in which in at least one cylinder, combustion of a fuel in a fuel/air mixture introduced into the cylinder takes place. Upon the occurrence of knocking, a baseline ignition angle in the at least one cylinder is retarded in steps, using a knock control system, to an adjustment angle from the basic ignition angle. When the adjustment angle exceeds a definable threshold value, activation of the knock prevention operation mode occurs, in which context an additional action reducing the knock susceptibility of the fuel/air mixture is taken and the adjustment angle is decreased so that the baseline ignition angle is advanced.

Abstract: A method and a device for fault detection or diagnosis may be used on a multi-cylinder internal combustion engine with a knock sensor. For diagnostic purposes an instantaneous reference value formed from the sensor signal may be compared with predefinable upper or lower reference threshold levels. If the instantaneous reference value exceeds or falls below the thresholds to a predefinable extent, a malfunction is detected. The reference levels correspond, for example, to the background noise present in knock-free operation. The fault detection or diagnosis may be performed only for the cylinder which emits the loudest noise or from which the loudest noise is recorded.

Abstract: A method for controlling knocking in multi-cylinder internal combustion engines in KC emergency operation and at activated guide-cylinder function are provided by which a torque loss is able to be avoided at low application expenditure and the functionality desired by the guide-cylinder function is maintained even in KC emergency operation. In KC emergency operation and when the guide-cylinder function is activated, cylinder pairs are formed from the cylinders operating in each case at a 360° offset. Each twin pair having at least one cylinder to be guided is assigned at least one of the available guide cylinders, so that the ignition timing retard of the cylinder pair to be guided is based on the ignition timing retard of the associated guide cylinder. Only when the number of available guide cylinders is insufficient will a safety retard timing be triggered, in which an ignition angle is adjusted which has been predefined for all cylinders.

Abstract: A device having a monitoring circuit for a knock control and a control circuit (10) which initiates substitute measures in the event of a fault in the knock control, depending on the output signal (f) of the monitoring circuit, is described. The control unit is designed, for example, so that the number of fuel injection operations per operating cycle of a cylinder of the engine is increased as the substitute measure.

Abstract: A method and a device for controlling knock in response to the failure of a phase detector are described, which implement the normal, cylinder-selective knock control under the condition, that the dual ignition is not activated. If the dual ignition is activated when the phase detector fails, then the knock control is carried out, using a non-cylinder-selective measure. Such a non-cylinder-selective measure could include safety-ignition retard or knock control, using one knock-detection threshold value for all of the cylinders.

Abstract: An ignition apparatus including a primary and a secondary winding for producing a spark voltage, an ion current detection circuit for producing an ion current signal, a slope detector and a knock detector. The slope detector determines when the ion current signal exhibits a slope indicative of a time period when knock is likely to occur, and de-asserts a knock reset signal. The knock reset signal holds the knock detector in reset, thus disallowing or masking the processing of signals by the knock detector that may be mistaken for knock.

Abstract: The invention relates to a method for knock control of an internal combustion engine, a knock detection being carried out on the cylinders of the internal combustion engine and a moment of ignition being retarded by a specifiable value as a function of detected knocking combustion in at least one of the cylinders, the system including at least two evaluation electronics and at least one cylinder being assigned to each of these evaluation electronics, and the knock sensor signals assigned to the cylinders being evaluated by the evaluation electronics assigned in each case, and the knock detection and the specification of the moment of ignition being effected by a control electronics, and the evaluation electronics being monitored for functionality.

Abstract: In the diagnostic method for detecting erroneous operation of a knock sensor of an internal combustion engine an actual reference level is formed from knock sensor signals generated by the knock sensor; then two minimum knock detection thresholds consisting of rotation speed values are defined and compared with rotation speed to test whether or not rotation speed exceeds each minimum knock detection threshold; the reference level is then compared with at least one of an upper reference level threshold and a lower reference level threshold, but only with the upper reference level threshold when a lower minimum knock detection threshold is exceeded, and a diagnostic signal indicative of a knock sensor fault or error is generated when the reference level exceeds the upper reference level threshold or falls below the lower reference level threshold, if and only if engine rotation speed exceeds at least one of the minimum knock detection thresholds.

Abstract: A method for error detection during an evaluation of sensor signals, in particular during an evaluation of output signals of knock sensors in an internal combustion engine, with at least one sensor and an evaluating device connected therewith, the method includes the steps of forming at least one variable reference level from output signals of a sensor or sensors; comparing the variable reference level for error detection with upper and/or limiting values; making a conclusion about an error in the case of a predeterminable exceeding of the upper and/or exceeding of the lower limiting value by the actual reference level; and forming at least one limiting value in dependence on preceding reference values.

Abstract: A method and a device for fault detection or diagnosis are described which are used on a multi-cylinder internal combustion engine with a knock sensor. For diagnostic purposes an instantaneous reference value formed from the sensor signal is compared with predefinable upper or lower reference threshold levels. If the instantaneous reference value exceeds or falls below the thresholds to a predefinable extent, a malfunction is detected. The reference levels correspond, for example, to the background noise present in knock-free operation. The fault detection or diagnosis is performed only for the cylinder which emits the loudest noise or from which the loudest noise is recorded.

Abstract: To obtain a knock control apparatus for internal-combustion engine having a function of judging whether or not the causes for failure have been solved for returning to normal knock control at the time of the solution, and capable of easily judging failure even in a failure mode in which it is difficult to raise the filter value and it is difficult to judge the failure.