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We developed a novel method for reducing the engine noise associated with the high-pressure fuel system in gasoline direct-injection (DI) engines. We focused on the level of noise at idle running speed, because at the idle state, engine noise is the only noise source to the driver. The dominant vibration source of the high-pressure fuel system was fuel pulsation from the high-pressure fuel pump and activation noise of the solenoid-drive injector. To reduce the noise of the idling engine, we focused on the vibration transmission path from the high-pressure fuel system to the cylinder head, which results in noise radiation from the engine block. Next, we focused on the radiation noise associated with the pressurization event of the high-pressure fuel pump. To reduce the vibration transmission from the high-pressure fuel system to the cylinder head, the fuel rail and the injector were isolated from the cylinder head by avoiding metal-to-metal contact.

In this paper, we develop a methodology to enable the isolation of the heat release contribution of knocking combustion from flame-propagation combustion. We first address the empirical modeling of individual non-autoigniting combustion history using the Wiebe function, and subsequently apply this methodology to investigate the effect of autoignition on the heat release history of knocking cycles in a spark ignition (SI) engine. We start by re-visiting the Wiebe function, which is widely used to model empirically mass burned histories in SI engines. We propose a method to tune the parameters of the Wiebe function on a cycle-by-cycle basis, i.e., generating a different Wiebe to suitably fit the heat release history of each cycle. Using non-autoigniting cycles, we show that the Wiebe function can reliably simulate the heat release history of an entire cycle, if only data from the first portion of the cycle is used in the tuning process.

In this paper, we investigate the effects of autoignition on the heat release characteristics of a spark-ignition (SI) engine, under knocking conditions. In a normal, flame-propagation combustion, the heat release rate increases smoothly to a maximum, and then progressively decreases as the entire mixture is consumed. When autoignition occurs, the heat release rate profile shows a departure from its normal profile: since autoignition results in an explosive combustion, an abnormal rapid increase in heat release rate is generated, with significantly higher peak heat release rates and faster fuel consumption. Three distinct heat-release-rate profiles for autoignition can be identified at different engine speeds, which differ in the phasing of the sudden increase in release rate due to autoignition, relative to the peak release rate due to normal combustion.

The Wavelet Transform (WT) has been developed two decades ago, and has since then been put to use in an increasingly wide array of applications. The WT provides a time-scale analysis of a signal. Compared to the widely-popular Fourier Transform (FT), originally developed two hundred years ago, the WT provides the time-evolution of the signal at different scales. The Discrete Wavelet Transform (DWT) is a computationally efficient implementation of the WT, in which the time-scale analysis is performed on a dyadic scale. The DWT is very suitable for knock detection systems, since it can provide the history of the knock signal at discrete scales within a crank angle window. It allows for the extraction of a multitude of features from the time-scale plane. Moreover, the DWT is suitable for real-time knock detection implementations on engine control units.

This paper describes a cold start emission reduction system developed for a 3.0L V6 test vehicle in order to meet SULEV emission regulations. The emphasis of this research is how the system can be used to meet SULEV emission standards without the need for a heavily loaded catalyst. A fuel-vaporizing device has been developed that generates vaporized fuel to be consumed during engine start up. The device allows for lean A/F ratio control during engine start and idle and is called a Combustion Stabilizing Device (CSD). A vehicle with a CSD mounted to the engine was tested in an emission lab. The test vehicle resulted in approximately 50% HC emission reduction in the first 20s of engine startup and had a catalyst warm-up time to T50 (50% converter efficiency) of less than 20s.