Abstract
This paper deals with the vibroacoustic behavior of an electric window-lift gear motor for automotive vehicle which consists of a direct current (DC) motor and a worm gear. After describing the overall vibroacoustic behavior of this system and identifying the various excitation sources involved, this study focuses on the excitation sources associated to the contacts between brushes and commutator. To that end, a specific test bench is designed. It makes use of a modified gear motor for which various specific rotors are driven with an external brushless motor. It allows the discrimination of some excitation sources associated to the contact between brushes and commutator by removing them one after the other. The respective weight of friction, mechanical shocks, electrical current flow, and commutation arcs occurring jointly at the brush/commutator interface are dissociated and evaluated. The friction and the mechanical shocks between brushes and commutator blades increase the vibroacoustic response of the window-lift gear motor. The flowing of electrical current in brushes/commutator contacts tends to moderate the frictional component of excitation sources, while commutation arcs induce their rising, leading to a global additive contribution to the dynamic response.
Highlights
Like other performances offered by an automotive vehicle such as safety, dynamics and fuel economy, the acoustic comfort within the passenger compartment has to be considered closely in the design process
A modified configuration which required an external drive motor is necessary to analyze the influence of electrical current flow, commutation arcs, mechanical shocks and friction noise between brushes and commutator blades on the window-lift gear motor vibratory response
EXPERIMENTAL RESULTS AND DISCUSSION 3.1 Standard configuration The use of the test bench in standard configuration allows for characterizing the overall vibroacoustic behavior of the window-lift gear motor
Summary
Like other performances offered by an automotive vehicle such as safety, dynamics and fuel economy, the acoustic comfort within the passenger compartment has to be considered closely in the design process. Excitation source Mechanical shocks between brushes and commutator blades Commutation arcs Noise friction between brushes and commutator blades Periodic fluctuation of the tangential electromagnetic forces Periodic fluctuation of the radial electromagnetic forces Shaft misalignment and mechanical imbalance Rotor/stator contacts at bearings and axial pads Worm gear meshing The standard configuration allows characterization of the window-lift gear motor vibroacoustic response and analyzing effects of operating speed and applied torque.
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