Search Results

Ethanol is regarded as the promising alternative fuel for gasoline to meet the strict low emission standard for spark ignition engines. In this study, the spray mixture formation process for different ethanol blended fuels, including E0 (gasoline), E85 (85% volume of ethanol and 15% volume of gasoline) and E100 (ethanol), has been evaluated using hole-type nozzle by the measurement of Laser Absorption Scattering (LAS) technique in a constant volume vessel. Based on the principle of LAS, the quantitative vapor and liquid phase distribution from different ethanol blended fuel can be obtained by the light extinction regime. Aiming to analyze the effect of mixture formation and evaporation for different components of blended fuel or pure gasoline and ethanol, the vapor distribution of gasoline was determined by using p-xylene, which had similar physical properties to gasoline, especially higher boiling temperature components, and higher absorption for ultraviolet.

An alternative to the current drum brakes, with the increased requirements of todays daily service are disc brakes, in that they offer, in contrast to the drum brakes, the following technical advantages and in turn enhance the active safety of modern commercial vehicles when braking: Enhanced brake pedal-feedback and actuation Improved efficiency Little performance losses when high thermal loads occur (fading). In order to be able to determine the improvement potential of disc brakes they will be compared to the commonly employed Simplex drum brakes. Both wheel brake systems (disc-/drum brakes and all variations) were tested on a computer controlled brake dynamometer and in field tests using a heavy duty commercial vehicle (class 8). The results are compared and conclusions drawn regarding “advantages/disadvantages”.

The effort of gear noise reduction has traditionally focused on minimizing transmission error. On the other hand, gears vibration characteristics are also known to influence gear noise strongly. With the thin helical gears, therefore, the entire gear noise mechanism is clarified quantitatively by experimental analysis, and a dominant factor is specified. The analysis has shown that meshing force is the most significant factor. Thus, innovative gear structure has been devised, which aggressively controls meshing force characteristics like a dynamic vibration reducer. Redesigned gears have successfully improved gear noise. These experimental technologies and design methods can be applied to general gear noise problem in order to conduct optimization.

A new approach of modeling is put forward to representing functions of clutch and brake directly, and their functional models are proposed in this report. Rotary motion is the most important type of motion for transmitting the kinetic energy, so many rotary parts and apparatus, for example the crutches and brakes, are used in most of machines. It is difficult to model function of the rotary element directly without relying on its structure by the conventional modeling approaches, for example the finite element method. The basic concept of the proposed approach is introduced, and the functional models of the hydraulic clutch with multiple plates, the clutch with vibration absorbing mechanism, the disc brake and the band brake are presented. Simulation results verify validity and usefulness of the proposed approach.

The mixture distribution and in-cylinder flow field inside the combustion chamber of a spark ignition engine with a swirl control intake system were measured by a pair of laser two-dimensional visualization techniques. The planer-laser-induced exciplex fluorescence technique was used to visualize the in-cylinder mixture formation by obtaining spectrally separated fluorescence images of liquid and vapor phase fuel distributions. The particle image velocimetry (PIV) was used to obtain the images of in-cylinder flow field. Experiments were carried out under various swirling conditions (from high [Rs=3.8] to low [Rs=0.4] swirl rates) to clarify the effect of swirl rate on mixture formation during the intake and compression strokes. Under the high swirling condition, fuel vapor was spread and rotated along the cylinder wall by the swirling flow during the compression stroke.

With the aim of elucidating the mechanism generating knock, an examination was made of the preflame reaction behavior of end gas in the combustion chamber in the transition from normal combustion to abnormal combustion characterized by the occurrence of knocking. Simultaneous measurements were made in the same cycle of the light absorption and emission behavior of the OH (characteristic spectrum of 306.4 nm), CH (431.5 nm) and C2 (516.5 nm) radicals in the end-gas region using spectroscopic methods. The absorbance behavior of a blue flame prior to autoignition is believed to be an important factor in the mechanism causing knock.

Given the legal requirements for quality assurance of passenger car exhaust emissions worldwide we define our quality assurance system and present the emission laboratories of the Mercedes-Benz assembly plants Sindelfingen and Bremen. We developed a hierarchically structured, multi-level computer system, which enables us to automize emission test procedures, calibration, maintenance of measurement systems and documentation of exhaust data. Test cell computers coordinate the different components of the test cells and perform maintenance and calibration of measurement devices, thus guaranteeing a high measurement quality with reasonable economy. The coordinating level computer, the emission host system (EHS), processes test parameters, controls and supervises the test sequences and evaluates the test results on a statistical basis.

The purpose of this research was to present and analyze a previously unreported mechanism of injury within the automotive crash environment - spinal burst or compression fractures due to a vertical force component. Spinal burst fractures are comminuted fractures of the vertebral body which are often associated with retropulsed bone fragments into the spinal. Compression fractures are less traumatic fractures of the vertebral body with minimal comminution. Both fracture types can have varying degrees of neurologic deficit. The mechanism of injury is hypothesized to be a high energy compressive load along the axis of the spine initiated through the buttocks and pelvis or through torso augmentation (inertial loading of the lumbar spine by the torso). Four crashes are presented as evidence of this injury mechanism within the automotive crash environment: two in the United States and two in Germany.