An exhaust system includes an exhaust duct having an internal surface defining an exhaust gas passage extending along an axis. At least one sensor opening is in the exhaust duct and is configured to receive an exhaust gas sensor. A wall is positioned within the exhaust gas passage to extend at least partially around the at least one sensor opening. The wall has an inner wall surface defining an internal volume. A plurality of inlet pipes are in fluid communication with the internal volume, and each inlet pipe extends from a first end open to the internal volume to a second end that is distal from the first end. Each inlet pipe includes a plurality of inlet apertures.

Methods and systems are disclosed for operating an engine that includes a knock control system. The methods and system provide for repurposing the engine knock control system to detect and mitigate piston slap. The methods and systems also seek to increase the signal to noise ratio for detecting piston slap.

A means of detecting the in-situ fuel-to-air-ratio (FAR) in a combustor or flame zone using a Fourier-based flame ionization probe is presented. The use of multiple excitation frequencies and its detection at certain frequencies or combinations of harmonics of those excitation frequencies, namely, the inter-modulation distortion, provides a novel means of extracting a high signal-to-noise ratio (SNR) FAR measurement in a combustor.

The disclosure relates to a method and a device for diagnosing an internal combustion engine of a powertrain. The powertrain includes the internal combustion engine and a transmission unit, and the diagnosis is carried out using a running irregularity signal, where potentially a gear change is actively requested. The method includes ascertaining a diagnostic value of the internal combustion engine during operation using the running irregularity signal of the internal combustion engine. The powertrain is operated using a diagnostic gear of the transmission unit. The method also includes detecting the diagnostic gear which is engaged in the transmission unit while ascertaining the diagnostic value; and comparing the ascertained diagnostic value with a predefined diagnostic threshold value and comparing the diagnostic gear of the transmission unit with at least one predefined gear of the transmission unit.

A method for transmitting the cylinder pressure data of a plurality of cylinder pressure sensors to a central processing unit, characterized by the use of a communication system for isochronous data transmission comprising a data bus, whereby the plurality of cylinder pressure sensors and the central processing unit are connected via the data bus, whereby each of the plurality of cylinder pressure sensors are combined with a data acquisition unit and a data communication unit to form a measurement node, whereby the cylinder pressure data is transmitted from the measurement node to the central processing unit via a time-slot method.

A method is provided for adjusting timing of fuel injection into a combustion chamber of a compression-ignition engine. The method includes detecting a request for zero torque generation by the engine and cutting-off delivery of fuel into the combustion chamber during the detected zero torque request. The method additionally includes issuing a command to inject a test quantity of fuel into the combustion chamber during the detected request for zero torque generation. The method also includes assessing a timing delay between the command to inject the test quantity of fuel and a start of the test quantity injection, and determining a compensation for the assessed timing delay. The method additionally includes detecting a request for positive torque generation by the engine. The method further includes commanding a shift in the timing of fuel injection into the combustion chamber by the determined compensation during the engine's positive torque generation.

A method and system for predicting the occurrence of a knock which will have a predetermined intensity or higher (intense knock) in an engine that burns an air-fuel mixture of gasoline fuel. The pressure in a combustion chamber is detected during an initial stage of combustion. This pressure is compared with a preset reference value to determine whether or not the cylinder inner pressure exceeds the reference value during the combustion. When the cylinder inner pressure exceeds the reference value, it is predicted that the intense knock will occur before an end of the combustion. If the intense knock is predicted, additional fuel or other material can be injected into the combustion chamber to prevent the occurrence of the intense knock.

Methods and systems are provided for reduction of VDE harmonics and improvement in the phase alignment of powertrain sensor signals that are asynchronously tasked. In one example, torque converter slip control is improved in a variable displacement engine by processing a raw torque converter turbine speed signal with a moving average filtered engine speed signal. By determining an actual delay between the sampled signals and adjusting a downstream filter parameter, a desired delay can be provided between the samples to align the phases and reduce the signal harmonics.

A method for predictive maintenance of components of an internal combustion engine by a structure-borne sound sensor includes: recording vibrations of the components of the internal combustion engine by at least one structure-borne sound sensor; and during operation of the internal combustion engine, continuously checking a release for diagnosing a wear condition of the components of the internal combustion engine. The one or more structure-borne sound sensors, which are arranged at one or more positions on the internal combustion engine, record measurement signals and forward them to evaluation electronics. The measurement signals are time-synchronized to a characteristic state of the internal combustion engine or the measurement signal recording is time-triggered. The time-synchronized or triggered measurement signals are decoded into measurement data. The decoded measurement data is subjected to a signal transformation. One or more spectrograms are generated from the signal transformation.

Disclosed is a method for detecting physical stoppage of an internal combustion engine, including: at least four cylinders, a set of cylinder pressure sensors, configured such that, over the course of a combustion cycle of the engine, there is at least one cylinder in the compression or expansion phase whose pressure is measured by a pressure sensor of the set, the method including the following steps: measuring the pressure in a cylinder in the compression or expansion phase, calculating, from the pressure measured in the cylinder, a ratio between a pressure variation in the cylinder and the pressure in the cylinder, and detecting a physical stoppage of the engine if the measured pressure is decreasing and if the calculated ratio is constant.