Hydraulic hybrid regenerative braking

Ofori-Teiko, Joel Nana Yaw
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Traditional friction brakes are wasteful in their method of slowing down a moving vehicle. They typically slow down a moving vehicle by converting the kinetic energy of the car into other forms of energy like friction energy and heat energy. To reduce the wastage of energy, regenerative braking, a method for capturing some of the energy that would have otherwise been lost has been devised. This stored energy is reused by the vehicle when next the accelerator pedal is depressed. Regenerative braking has commercially taken a form that captures energy in the form of electricity stored in battery packs. Because of this, cars that employ the technology either use hybrid electric vehicles or fully electric of vehicles. In trying to improve the consumers’ choices regarding regenerative braking, this project seeks to test the concept of regenerative braking using hydraulics. This form of regenerative braking comes in two forms: parallel hydraulic hybrid regenerative braking and series hydraulic hybrid braking. The Parallel hydraulic hybrid regenerative braking system is chosen as the focus for this study for reasons discussed in subsequent session of the report (1.7). In testing the Parallel hydraulic hybrid regenerative system, fatigue tests were conducted on the pressure tanks since they were the most prone component to failure. Again, fatigue tests were conducted on the pressure tanks. The weight of the entire system was evaluated as was the system’s effect on braking distance. The amount of energy the system stored at peak was also estimated using simple assumptions. The results from this study prompted a very simple conclusion. Parallel hybrid hydraulics are a capable replacement than the widely employed electric hybrid regenerative system. However, a key component of the Hydraulic Hybrid Vehicles (HHV), its pump/motor, is scarce and not a lot of research has gone into it. Thus, it would be a difficult feat to commercialize the HHV. The conclusion of this project is that, HHVs can replace electric hybrid regenerative braking systems but not until enough research has gone into the pump/motor.
Capstone Project submitted to the Department of Engineering, Ashesi University in partial fulfillment of the requirements for the award of Bachelor of Science degree in Mechanical Engineering, May 2020
braking system, regenerative braking, parallel hybrid hydraulic system, energy conservation