Design, finite element analysis and energy assessment of a hinged speed bump energy harvester with an integrated wrong-way vehicle deterrent

Abstract

Speed bumps make vehicles lose energy, and many studies have proposed recovering some of it for street lighting. This paper describes a hinged speed bump harvester that drives three DC generators through a rack-and-pinion, gear and chain train, uses a two-stage variable pitch  spring to give a full 80 mm stroke across vehicle masses, and carries cast iron spikes to deter wrong-way driving. Static finite element analysis showed that redesigning the bump geometry and supports cut peak deformation from 4.13 mm to 0.11 mm and peak stress from 484 MPa to 6.9 MPa. The spring reached 397 MPa under a 1500 kg vehicle, with a minimum factor of safety of 4.2. An energy balance shows that, with one 700 kg vehicle every 15 s,  traffic supplies at most 0.88 kWh per day, or 36.6 W on average. Allowing for conversion losses, realistic output is 0.26–0.53 kWh per day, enough for one or two 24 W LED street lights for 12 h and far below an earlier estimate of 6.2 kWh per day. The estimated cost for three sections is Rs 69,561. A small prototype demonstrated the mechanism qualitatively.