This Small Business Innovation Research (SBIR) Phase I project proposes to develop a hydraulic regenerative shock absorber and charge system for hybrid trucks. An appreciable amount of energy is lost in a typical suspension as heat, especially in heavy vehicles. Existing technologies have been unable to efficiently capture this energy in a cost-effective manner. This project will entail the modeling, design, fabrication, and testing of a hydraulic-electric energy harvesting unit, along with the power electronics and energy storage subsystem to charge hybrid truck batteries. The objective of the project is to study and prove the feasibility of a regenerative shock absorber as a disruptive hydraulic energy harvesting mechanism on heavy trucks. Emphasis will be on the specific challenges of converting high force small amplitude oscillations into electricity that can interface with hybrid charge systems. Work will focus on a proof-of-concept demonstration and a determination of the increased efficiency possible on a hybrid vehicle using the internal piston/integrated-generator regenerative shock absorber mechanism.
The broader impact/commercial potential of this project is significant as the foundational technology can be applied to a wide range of vehicles, systems and industrial applications in diverse industries. The technology has the potential to save millions of dollars per year in fuel for fleet operators, and simultaneously reduce carbon emissions across the United States. Hybrid vehicles traditionally have a single energy regeneration source (braking) to charge batteries. Effectively incorporating a secondary regenerative charge system may open doors to many new regenerative technologies that work in unison to charge hybrid vehicle batteries, thus allowing for significant reductions in waste energy. The market potential for the technology is considerable, and includes trucks, military vehicles, transit buses, passenger vehicles, and rail. When incorporated into conventional non-hybrid platforms, the technology can improve fuel economy by displacing alternator load. In addition to vehicular applications, the research may, on a broader scale, lead to enabling technologies for compact, sealed, and efficient hydraulic actuators and energy harvesters. This will have applications in other fields such as aviation, industrial machinery, and robotics.
Project Intellectual Merit & Broader Impacts For over 100 years since the introduction of the first shock absorber in 1898, the traditional paradigm in the industry has been to create damping by dissipating energy as heat. GenShock disrupts this paradigm by damping through harvesting energy directly as electricity. In this Phase I and IB SBIR, GenShock’s capability to provide superior damping while generating power was demonstrated. GenShock is positioned to transform the shock absorber industry -- a business engaged in designing, manufacturing, and selling commodity devices -- with an important clean and regenerative technology that captures energy, pays for itself in fuel savings, and improves ride, handling and safety. Broader contributions to technical fields include: Hydraulics: The Phase I SBIR contributed to the field of hydraulics by demonstrating the feasibility of fully-sealed, compact, efficient, and high-power density hydraulics. In a miniaturized form factor, and without any external hydraulic components, the GenShock unit demonstrated high peak efficiencies of energy capture. These efficiencies are largely unprecedented in hydraulic systems designed to capture energy over a wide dynamic range of input velocities and amplitudes. In addition, the design architecture is a disruptive form-factor for hydraulics integrators because it delivers high-power density capabilities in a small package. Electronics: The GenShock controller developed under this Phase I SBIR contributed to the field of regenerative power electronics systems, specifically, by demonstrating the feasibility of decoupling kinematic characteristics on a mechanical device from energy output of the system. In application, this allows the controller to affect a given damping curve on GenShock irrespective of the battery management algorithms governing power output from the controller to the truck. This advance in power electronics and their control may have deep implications for additional regenerative technologies that are likely to be introduced into vehicles in the coming decade. Energy-Harvesting: Linear and/or vibration energy harvesting has focused in recent years on low power technologies, for example, piezoelectrics for microwatt energy capture. GenShock has the potential to be a broadly-applied platform technology for energy capture in the realm of tens of watts to many kilowatts. This may open the door to a variety of new fields and applications of energy harvesting including civil (i.e. from bridge dampers), marine (i.e. to power floating platforms), and industrial (i.e. machinery vibration and noise mitigation). Project Outcomes During the conduct of the Phase I and Phase IB SBIR, Levant Power successfully modeled, simulated, designed, developed, fabricated, and tested a hydraulic energy recovery system ("GenShock") to capture waste energy in truck suspensions. Results demonstrate energy capture ability exceeding 600W RMS, controllable damping, and performance highly correlated to the predictive models developed for the project. Under simulated truck road profile testing, the single shock and controller generated 40.3 W average. Assuming full tractor/trailer retrofit, this energy translates to roughly $410 in fuel savings per year from alternator load relief. Primary activities performed include: the development of a predictive Matlab GenShock model, design and fabrication of a turnkey hydraulic regenerative shock absorber, exhaustive prototype testing and characterization, and value proposition analysis. Additional key project outcomes demonstrated: significant energy is available in the suspensions of heavy trucks (400 to 1,400 watts), and this is typically dissipated as heat; GenShock is able to efficiently convert this energy by creating a damping force, with conversion efficiencies exceeding 50%; GenShock was able to mimic the stock damping curve, or in software to vary the damping force; preliminary payback analysis and cost estimates suggest GenShock can recover its initial investment in approximately 1.7 years from fuel savings. Testing proved that GenShock is an adaptive damper (damping force can be set in software) that recovers meaningful suspension energy. In summation: GenShock represents a disruptive capability to capture waste energy, diminish fuel consumption and vehicle emissions, improve ride, handling and performance, and pay for itself through normal vehicle operation.
