A Novel, Elastically-Based, Regenerative Brake and Launch Assist Mechanism

This paper presents the development of a regenerative brake and launch assist (RBLA) mechanism that stores energy in an elastic medium. Automotive regenerative braking systems harness kinetic energy while a vehicle decelerates, and subsequently uses that stored energy to assist propulsion. Commercially available hybrid vehicles use generators, batteries, and motors to electrically implement regenerative braking and increase overall vehicle efficiency. With the intent to apply regenerative braking technology to conventional automobiles equipped with only an internal combustion engine, a spring-based mechanical device is proposed. This RBLA concept implements clutches, gears, a ratchet and a spring. The mechanism captures energy from, and releases energy to, an additional shaft allowing the axle to continually rotate. Governing equations were formulated and validated by a dynamic simulation. In creating the detailed design, an optimization determined ideal spring and mechanism dimensions. A physical prototype was designed and fabricated to demonstrate the concept. A model of the proposed spring-based RBLA shows an increase in the urban fuel efficiency for an average sedan.