A piezoelectric pressure sensor is characterized by a piezoelectric transducer having substantially parallel piezoelectric plate faces oriented in planes that extend substantially parallel a principal longitudinal axis of the sensor, a pair of clamping members engaging the piezoelectric plate faces, a membrane cap covering the clamping members and mounted on a stem to define an enclosed protective chamber that isolates the piezoelectric transducer and the clamping members from an environment outside the membrane cap. The membrane cap has a membrane wall engaging outside faces of the clamping members. The membrane wall undergoes inward deflections in response to pressure increases in the environment outside the membrane cap. The clamping members undergo corresponding inward deflections in response to the inward deflections of the membrane wall. The inward deflections of the clamping members act on the piezoelectric plate faces, resulting in deformations of the piezoelectric transducer that produce corresponding electrical signals.

A piezoelectric pressure sensor is characterized by a piezoelectric transducer having substantially parallel piezoelectric plate faces oriented in planes that extend substantially parallel a principal longitudinal axis of the sensor, a pair of clamping members engaging the piezoelectric plate faces, a membrane cap covering the clamping members and mounted on a stem to define an enclosed protective chamber that isolates the piezoelectric transducer and the clamping members from an environment outside the membrane cap. The membrane cap has a membrane wall engaging outside faces of the clamping members. The membrane wall undergoes inward deflections in response to pressure increases in the environment outside the membrane cap. The clamping members undergo corresponding inward deflections in response to the inward deflections of the membrane wall. The inward deflections of the clamping members act on the piezoelectric plate faces, resulting in deformations of the piezoelectric transducer that produce corresponding electrical signals.

A method of detecting uncontrolled combustion in an internal combustion engine includes sampling in-cylinder pressure sensor configured to measure pressure in a cylinder of the engine and generate a pressure signal, calculating a combustion intensity metric based on the pressure signal, determining a parameter describing how close the engine is to an uncontrolled combustion condition based on the combustion intensity metric, and controlling a substitution rate of a first fuel and a second fuel based on one or more of the parameter and the combustion intensity metric.

An ignition timing control device for an internal combustion engine includes a storage device and a processor. The storage device stores a first learned neural network and a second learned neural network. The processor is configured to perform, in a next cycle where ignition timing is delayed, control to delay the ignition timing in a cycle after the next cycle based on a difference between a predictive value of an estimate of a value representing knocking intensity calculated with use of the second learned neural network and the estimate of the value representing the knocking intensity calculated with use of the first learned neural network. When the difference is larger than a predetermined set value, the processor is configured not to perform the control to delay the ignition timing in the cycle after the next cycle.

An ignition timing control device includes bandpass filters each configured to pass and output only a specific frequency band for the output value of a knocking sensor, a storage device storing first learned neural networks configured to receive the output values of the bandpass filters in respective frequency band, and a processor. Each of the first learned neural networks is pre-learned to output an estimated value for a value representing knocking intensity when receiving the filtered output value of the bandpass filter. The processor calculates an optimal estimated value using a part of acquired estimated values for the value excluding a unique estimated value, and executes retarding control of an ignition timing based on the calculated optimal estimated value.

A pressure detection signal processing device, engine control system, and non-transitory computer readable medium storing a program are provided. A current-voltage conversion part that converts a current signal corresponding to charge generated by a piezoelectric element in accordance with received pressure into a voltage signal, and digital signal processing parts that perform correction for removing a drift caused by a leakage current of the piezoelectric element on the voltage signal through digital signal processing are provided. The digital signal processing parts include a differentiation processing part that performs differentiation processing on the voltage signal, an integration processing part that performs integration processing on the signal having been subjected to the differentiation processing, and an integration processing part that further performs integration processing on the signal having been subjected to the integration processing.

A method for managing knock in a cylinder of an internal combustion engine, in a system including at least one acoustic sensor and a processor, in order to take into account acoustic pollution resulting from a noise, the method including: forming and digitizing the signals of the acoustic sensor, applying a bandpass filter to obtain a filtered noise, determining an adjustable gain-correction function using a gain-correction curve and, depending on the angular position of the end of injection, the point on the gain-correction curve to be used to convert the filtered noise into a corrected knock score, comparing a corrected knock score thus obtained to a knock decision threshold, to correct the timing advance, the gain-correction curve being defined by a calibration value and four angular points obtained by calculation based on the start and end positions of a knock-observation window and on a known characteristic of the noise.

A knocking sensor (18) detecting vibration of an engine body (1) and a pressure sensor (19) detecting a pressure of a combustion chamber (5) are provided. A value representing the knocking strength is acquired from output values of the pressure sensor (19). Weights of a neural network are learned using a value representing the vibration of the engine body (1) detected by the knocking sensor (18) as an input value of the neural network and using the acquired value representing the knocking strength as training data. The value representing the knocking strength is estimated from the output values of the knocking sensor (18) by using the learned neural network.

A combustion control part of a control device for an internal combustion engine configured to calculate a first vibration level of an engine body at a first judgment frequency band of a second overtone of a specific frequency band based on vibration acceleration detected by a vibration sensor and, when the first vibration level is less than a predetermined first reference vibration level set in advance according to the engine operating state, to correct one or both of a target injection amount and target injection timing so that the first vibration level becomes the first reference vibration level or more.

A pressure detection device includes: a cylindrical body made of a conductor; a pressure receiver made of a conductor, the pressure receiver being mounted to one end side of the body and receiving pressure from the outside; a signal generator arranged inside the body, the signal generator being electrically connected to the pressure receiver and generating a signal corresponding to the pressure received by the pressure receiver; and a cover made of an insulator with a lower thermal conductivity than thermal conductivities of the body and the pressure receiver, the cover continuously covering an outer surface of the pressure receiver and a portion of an outer surface of the body, the portion being located at a side closer to the pressure receiver.