Silicon retainer ring integration in micro-turbine with thrust ball bearing support mechanism

Hergert, R. J.; Hanrahan, Brendan; Holmes, Andrew S.; Ghodssi, Reza

doi:10.1109/transducers.2011.5969503

Cited by 4 publications

(2 citation statements)

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“…Also the turbine wafer thickness was increased to 1 mm so that it could accommodate the retainer raceway on the back side and the rotor blades and guide vanes on the front side (see figure 3(b)) while leaving a sufficient thickness of silicon in between to withstand the thrust force applied to the bearing during operation. The process flow reported in [17] did not leave a sufficient silicon thickness above the bearing to support the normal load during operation, resulting in rapid failure of 10 mm diameter devices due to silicon fracture.…”

Section: Smt Designmentioning

confidence: 99%

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Performance of integrated retainer rings in silicon micro-turbines with thrust style micro-ball bearings

Hergert

Hanrahan

Ghodssi

et al. 2013

J. Micromech. Microeng.

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This work explores the performance of different silicon retainer ring designs when integrated into silicon micro-turbines (SMTs) incorporating thrust style bearings supported on 500 μm diameter steel balls. Experimental performance curves are presented for SMTs with rotor diameters of 5 mm and 10 mm, each with five different retainer designs varying in mechanical rigidity, ball pocket shape and ball complement. It was found that the different retainer designs yielded different performance curves, with the closed pocket designs consistently requiring lower input power for a given rotation speed, and the most rigid retainers giving the best performance overall. Both 5 mm and 10 mm diameter devices have shown repeatable performance at rotation speeds up to and exceeding 20 000 RPM with input power levels below 2 W, and devices were tested for over 2.5 million revolutions without failure. Retainer rings are commonly used in macro-scale bearings to ensure uniform spacing between the rolling elements. The integration of retainers into micro-bearings could lower costs by reducing the number of balls required for stable operation, and also open up the possibility of 'smart' bearings with integrated sensors to monitor the bearing status.

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Section: Smt Designmentioning

confidence: 99%

“…An earlier investigation of different retainer geometries in 5 mm-diameter SMTs was reported by us in [17]. Since the publication of the previous work, the fabrication process for the devices has been improved to allow us to successfully fabricate and test devices with a 10 mm rotor diameter.…”

Section: Introductionmentioning

confidence: 99%