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The objective of this investigation is to characterize the torsional characteristics of the hydrodynamic torque converter. Analytical and experimental techniques are used to quantify the relationship between torsional oscillations imposed on the pump to those at the turbine as a function of frequency, operating point and design. A detailed model of the hydrodynamic torque converter based upon one-dimensional flow theory is used to establish fundamental torsional behavior independent of the downstream mechanical system. A simplified linear spring-mass-damper representation of the hydrodynamic torque converter is derived whose coefficients are proportional to pump speed for a particular design. A transmission dynamometer test cell with the capability to produce torsional oscillations was used to develop frequency response functions for various torque converters in a transmission, operating at steady state conditions.

This paper presents a test methodology to determine the physical properties of stiffness and damping for powertrain rotating components using a free-free torsional frequency response measurement. The test methodology utilizes free-free boundary conditions and traditional modal test techniques applied to symmetric rotating components with substantially large bounding masses of known inertia. A modal test on the rotating component is executed by mounting accelerometers on opposing tangential bosses in the same direction on each of the inertial masses and impacting one of the bosses with a modal hammer to acquire frequency response functions (FRF's). Physical properties are then extracted from the FRF's using fundamental vibration relationships for an assumed two degree of freedom system. Stiffness and damping values for a variety of hollow tube carbon fiber drive shafts and a comparable steel-aluminum shaft are reported using the methodology presented.

General Motors' Chevrolet Volt is an Extended Range Electric Vehicle (EREV). This car has aggressive targets for all electric range with engine off and fuel economy with the engine on. The Voltec 4ET50 transaxle has gears, clutches, and shafts and controls that execute two kinematic modes for engine off operation or Electric Vehicle (EV) operation, and two additional kinematic modes for extended range (ER) operation. The Voltec electric transaxle also has two electric motors, two inverters, and specialized motor controls to motivate to execute each of those four driving modes. Collectively these are known as the Voltec Electric drive. This paper will present the design and performance details of the Chevrolet Voltec electric drive. Both the machines of the Voltec electric drive system are permanent magnet AC synchronous machines with the magnets buried inside the rotor. The motor has distributed windings.

Measurement of gear noise requires accurate measurement of gear mesh harmonic sound levels. The sound signal may include sidebands, such that the frequency bandwidth and computation method of respective “order tracking” analysis will have a profound effect on measured sound levels. A further consideration is the spatial distribution of the sound field inside typical passenger cars and light duty trucks, in which sound levels can change dramatically within small distances. This paper provides a discussion of the data processing and measurement location effects at hand. It explains their influence and provides guidelines for their selection.

Evaporative emission control system purge solenoid valves in passenger cars and light-duty trucks are a noise source that engenders customer complaint. Valveonly noise tests produce results that are inconsistent with measured system noise. Such tests fail to account for variables introduced in situ. This study investigates valve-induced structure-borne noise as the major source of system noise. It researches a theoretical method to relate structure-borne purge solenoid system noise requirements, valve-only, and vehicle mounting system dynamic requirements. It aims to validate the researched method and determine the nature of a valve-only bench test and a mounting system dynamic test. Several systems' noise levels, inertance, and acoustic responses were measured. The bench test vibration for each solenoid valve was also measured. This study discovered that the internal force of the purge solenoid may change with the mounting system compliance.

Typically pass-by noise evaluation is performed very late in the vehicle development cycle and any changes or modifications are costly, making an exterior modeling procedure compatible with both test and math-based techniques desirable. This paper demonstrates how the Airborne Source Quantification (ASQ) technique can be applied to modeling vehicle exterior noise. The results of this study also show that the source strength of individual sub-systems, i.e. the engine or transmission, can be determined independently from the full vehicle using a sub-system dynamometer. Results are correlated by assessing source strength and overall pass-by sound pressure level.