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Vibrations of a cup-shaped rotor in a bushless DC motor are investigated. The 4-phase motor has 12 pole pieces in the stator which is surrounded by a cylindrical, cup-shaped rotor with 14 magnets. The strong, pulsating magnetic forces acting on the rotor result in strong vibrations. Finite Element Analysis is used to analyze the vibrational pattern of the rotor. The impact of small changes in the dimensions of the rotor on its vibrational frequencies is also investigated. Details of FEA modeling will be presented and its predictions will be compared with the experimental data.

Pumps are usually tested for performance and efficiency as well as other pump characteristics. With the increased awareness of Noise, Vibration and Harshness (NVH) in the automotive industry, new standardized tests have evolved for testing pumps. Two major tests are the impedance and ripple tests. Information collected on these signatures of pumps is vital for the success of any Fluid Born Noise (FBN) analysis of these important components and the system in which they function. The purpose of this paper is to study the repeatability and reproducibility of such tests for the same pump. Production variability will be found when pumps of the same ‘category’ or part number are tested. The information presented here is important for the generalization of these tests and establishing them as a part of the research, development and design process. A set of pumps commonly used in the vehicle is put to the test.

Passengers' frequent requests are for less Noise, Vibration and Harshness (NVH) in the vehicle compartment. This and the reduction of noise and vibration levels from major sources like the engine necessitate better performance of other sources of noise and vibrations in a vehicle. Some of these sources are the hydraulic circuits including the power steering system. Fluid pulses or pressure ripples, generated typically by a pump, become excitation forces to the structure of a vehicle or the steering gear and represent a considerable source of discomfort to the vehicle passengers. Current power steering technology attenuates this ripple along the pressure line connecting the pump to the steering gear. Finding the optimum design configuration for the components (hose, tuner, tube, and others) has been a matter of experience-based trial and error. This paper is a part of a program to simulate and optimize fluid borne noise in hydraulic circuits.

Certain properties of fluid change with pressure, temperature and other operating system conditions. In automotive hydraulic systems driven by pumps, air usually enters the system as dissolved matter or very small bubbles. Such air will change certain properties of the fluid like the density, bulk modulus and viscosity. Measuring these properties for evaluating system performance in real operating conditions is one of the big challenges that face engineers. In this paper, the bulk modulus of certain power steering fluids is measured using standard impedance and flow ripple tests for pumps. The effects of pressure, temperature and speed on the bulk modulus are studied thoroughly.