METHOD FOR ENGINE WAVEFORM ANALYSIS AND FAULT DIAGNOSIS BASED ON SFB AND HHT

Traditional engine waveform analysis in time-domain fails to perform an accurate fault diagnosis when the fault waveform is very close to the normal waveform in time domain. A novel engine waveform analysis method is presented. In this paper, the aim is to perform fault diagnosis efficiently under such circumstances. This method is proposed by combining a new technique, called sensitive frequency band (SFB) selection, with the developed Hilbert–Huang transform (HHT). This can alleviate "mode mixing" by removing noise from the engine waveforms and reveal the time–frequency characteristics for a signal by deriving its time–frequency spectrum (TFS) distribution. The method is then applied to analyze the engine injector-pulse-width waveforms, and it works well for signal noise reduction and fault diagnosis.

Real Time Monitoring of Diesel Engine Injector Waveforms for Accurate Fuel Metering and Control

This paper presents the development, experimentation, and validation of a reliable and robust system to monitor the injector pulse generated by an engine control module (ECM) which can easily be calibrated for different engine platforms and then feedback the corresponding fueling quantity to the real-time computer in a closed-loop controller in the loop (CIL) bench in order to achieve optimal fueling. This research utilizes field programmable gate arrays (FPGA) and direct memory access (DMA) transfer capability to achieve high speed data acquisition and delivery. This work is conducted in two stages: the first stage is to study the variability involved in the injected fueling quantity from pulse to pulse, from injector to injector, between real injector stators and inductor load cells, and over different operating conditions. Different thresholds have been used to find out the best start of injection (SOI) threshold and the end of injection (EOI) threshold that capture the injector “on-time” with best reliability and accuracy. Second stage involves development of a system that interprets the injector pulse into fueling quantity. The system can easily be calibrated for various platforms. Finally, the use of resulting correction table has been observed to capture the fueling quantity with highest accuracy.

Diesel Engine Injector Waveform Monitoring in Real-Time for Fuel Efficiency

This paper presents the development, experimentation and validation of a reliable and robust system, which can be easily calibrated for different engine platforms, to monitor the injector pulse generated by an Engine Control Module (ECM) and feedback the corresponding fueling quantity to the real-time computer in a closed-loop Controller in the loop (CIL) bench in order to achieve optimal fueling. This research utilized Field Programmable Gate Arrays (FPGA) and Direct Memory Access (DMA) transfer capability to achieve high speed data acquisition and delivery. The research is conducted in two stages, first stage was to study the variability involved in the injected fueling quantity from pulse to pulse, from injector to injector, between real injector stators and inductor load cells, over different operating conditions. Different thresholds were experimented to find out the best start of injection (SOI) threshold and the end of injection (EOI) threshold that captured the injector “on-time” with best reliability and accuracy. Second stage involved development of a system that interprets the injector pulse into fueling quantity; the system can be easily calibrated to be used over various platforms. Finally, the use of resulting correction table was found to capture the fueling quantity with best accuracy.

Model-based ethanol blend estimation in flexible-fuel vehicles

This paper presents a model-based strategy estimating the ethanol content of an ethanol–gasoline blended fuel in flexible fuel vehicles. A steady-state parametric model relating engine speed, throttle angle, and air–fuel ratio to the fuel injector pulse-width is developed from physics. The parameters of this model are adapted and linked to percentage of ethanol content via a suitably defined metric. The proposed steady-state model structure is experimentally validated on a 2005 5.4L V8 Ford engine. The developed ethanol content estimation methodology is justified based on the combustion chemistry and physics involved. The methodology developed has a distinct advantage over previously proposed methods as it uses only the existing sensor set on a production vehicle.

Modeling and Excitation Torque Estimation of an Engine Cold-Test Stand for Evaluating Driveline Design and Fault Diagnostics

The fault detection process becomes difficult in engine cold-testing when the test stands undergo torsional vibrations excited by various engine harmonics. In the context of vibration suppression and assembly faults diagnostics, this paper focuses on three main aspects: cold-test stand modeling and validation, estimation of cold-engine excitation torque, and evaluation of a fuel injector pulse diagnostic test. To analyze the vibratory torque of the cold-test stand driveline, an engine excitation model comprising of inertia torque and unfired gas pressure torque is needed. The gas pressure torque cannot be determined in the absence of engine gas pressure measurements. It is shown that this excitation torque can be estimated by assuming that the net torque during the unfired engine cycle is zero and by utilizing the firing engine gas pressure torque in the combustion stroke. The estimated excitation torque is employed to validate models of different cold-test stands and also to examine various driveline design alternatives. Using embedded sensitivity functions, it is found that by changing the inertia and stiffness of the rubber coupling, the torsional vibrations can be suppressed. Finally, the modified design is evaluated for an injector pulse diagnostic test. It is shown that the design modifications can also enhance sensitivity to faults if the injector pulse test is carried out at higher speeds.