Mechanical Motion Rectifier Based Energy-Harvesting Shock Absorber

Abstract

Energy-harvesting shock absorber is able to recover the energy otherwise dissipated in the suspension vibration while simultaneously suppress the vibration induced by road roughness. It can work as a controllable damper as well as an energy generator. An innovative design of regenerative shock absorbers is proposed in this paper, with the advantage of significantly improving energy harvesting efficiency and reducing the impact forces caused by oscillation. The key component is a unique motion mechanism, which we called “mechanical motion rectifier (MMR)”, to convert the suspension’s oscillatory vibration into unidirectional rotation of the generator. An implementation of motion rectifier based harvester with high compactness is introduced and prototyped. A dynamic model is created to analyze the general properties of the motion rectifier by making analogy between mechanical systems and electrical circuits. The model is capable of analyzing electrical and mechanical components at the same time. Both simulation and experiments are carried out to verify the modeling and the advantages. The prototype achieved over 60% efficiency at high frequency, much better than the conventional regenerative shock absorbers in oscillatory motion. Furthermore, road tests are done to verify the feasibility of the MMR shock absorber, in which more than 15 Watts’ electricity is harvested while driving at 15 mph. The motion rectifier based design can also be used for other applications of electromagnetic vibration energy harvesting.

Large-scale vibration energy harvesting

“…So, Li, and Zuo et al . (Zuo, et al , 2011, Li et al , 2012) also proposed to use a mechanical motion rectifier, as shown in Figure 28, which can change the bidirectional vibration into smooth one-directional rotational motion of the motor, resulting in high efficiency and more robustness. Besides, the electromagnetic motor will provide DC voltage if DC motor is utilized.…”

A Comprehensive Review of the Techniques on Regenerative Shock Absorber Systems

“…Li, Zuo [47] proposed an innovative motion rectifier system, which can convert the up and down movement of the shock absorber into unidirectional rotation of the generator, shown in the Figure 11. The rack and pinion mechanism helps to convert and amplify the excitation displacement.…”

“…To obtain the stable damping force throughout the entire motion cycle, the designs are upgraded with two clutch systems [47,49,59]. These two clutches are installed facing each other on the drive shaft and both connected with same output shaft.…”

“…(a) The prototype of the regenerative shock absorber and (b) the integrated Mechanical motion rectifier, as proposed by Li, Zuo[47].…”

A Review on Mechanical Motion Rectifier for Energy Harvesting

“…The alternating motion of the motor and gears will quickly wear out the gears. So, Li and Zuo et al [25] also proposed using a mechanical motion rectifier, as illustrated in Figure 13, to convert the motor's bidirectional vibration into smooth one-directional rotating motion, resulting in higher efficiency and robustness. Furthermore, if a DC motor is used, the electromagnetic motor will supply DC voltage.…”