Office of Technology Transfer – University of Michigan

Two-Stage Hydraulic Regenerative Braking for a Bicycle

Technology #3252

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Categories
Researchers
Albert J. Shih
Managed By
Keith Hughes
Assistant Director, Physical Sciences & Engineering 734-764-9429
Patent Protection
US Patent 7,992,948

Background

The rising cost of oil and gas has increased the interest in the use and recapture of vehicular power in innovative ways. The stop-and-start pattern of driving or bicycling wastes energy whenever decelerating means throwing braking energy away as heat. If instead that energy is captured and reusing, overall efficiency increases and new opportunities can be created to use that energy that change the user’s experience. For example, bicycles typically rely on the rider for all of their power, and while significant speeds can be obtained after hard pumping of the pedals, starting from a dead stop takes substantial effort. If the braking energy could be trapped and stored, it would be available to boost the bike to regular operating speed from a standstill. Gas-electric hybrid vehicles employ a similar principle using batteries and electric motors, but ideally three- and four-wheeled vehicles would use a system without complicated drive electronics.

Technology

Researchers at the University of Michigan have designed a system for hydraulic regenerative braking, and have implemented it within the front hub of a bicycle wheel and onto a light truck chassis. Both systems use a set of hydraulic reservoirs to collect and store braking energy, and can release that energy on demand to propel the vehicle from a standstill or while climbing hills. Currently a full discharge of the reservoir can propel an adult male from 0 to 20 miles per hour. Originally the system required a special-purpose front wheel and fork for the bicycle, but the components have since been consolidated into a thinner wheel and hub capable of being retrofit to a standard front fork.

Applications and Advantages

Applications

  • Regenerative hydraulic system for braking in-nl-vehicles such as bicycles and automobiles

Advantages

  • Efficient re-use of kinetic energy that would-nl-otherwise be dissipated and lost during braking
  • Provides an exciting boost of acceleration-nl-to the bicycle