Experimental Analysis of the Vibroacoustic Response of an Electric Window-Lift Gear Motor Generated by the Contact Between Carbon Brushes and Commutator

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.

Electrical discharge machining of ceramic nanocomposites: sublimation phenomena and adaptive control

“…It is especially visible in the areas of spectral peaks associated with own frequencies of the ‘tool with guide nozzles–workpiece with fastening elements–machine’ system. During the detected friction contact, the vibro-acoustic amplitude was low and primarily defined by the speed of the relative movement of electrode surfaces and their hardness [137, 168, 169]. The wire rewinding speed was approximately 150 mm/s.…”

“…According to study results [169, 210, 211], sublimation of brass under vacuum conditions starts with zinc as the most fusible material at 450 °C (the melting point of zinc is 419.5 °C, whereas the melting point of copper is 1085 °C). At the same time, a nanoporous structure is formed in the remaining copper [169].…”

“…According to study results [169, 210, 211], sublimation of brass under vacuum conditions starts with zinc as the most fusible material at 450 °C (the melting point of zinc is 419.5 °C, whereas the melting point of copper is 1085 °C). At the same time, a nanoporous structure is formed in the remaining copper [169]. The studies showed that when brass sublimates under normal conditions in the presence of an air medium, a whitish needle-shaped film forms for zinc oxides at a temperature of ∼300 °C, a single-layer film of CuO at a temperature of 300–375 °C, a bilayer film of black CuO, and a dark red Cu 2 O at 375–1100 °C.…”

Numerical and experimental analysis of the vibroacoustic behavior of an electric window-lift gear motor

“…The contribution of some excitations sources to the vibroacoustic behavior of the gear motor has been previously studied. From experiments performed with several window-lift gear motors, Diop [11] showed that the weight of the tonal, compared with the broadband noise, is more than 80 % of the dynamic response in the frequency range [0-6 kHz]. Furthermore, in the same article, the weight of the sources taking place at the brushes/commutator interfaces (friction noise, mechanical shocks, commutation arcs) has been studied using a specific test bench which allowed the remove of them one after the other.…”

“…The vibratory response is measured thanks to a piezoelectric accelerometer glued on the outer face of the plastic housing close to the brushes/commutator contacts. It has been previously demonstrated that this accelerometer location allows for acquiring a signal level representative of the overall gear motor vibroacoustic response[11].…”