Regenerative Shock Absorbers Research Articles

Optimized design and characterization of motor-pump unit for energy-regenerative shock absorbers

The constant need to reduce emissions in the automotive sector has driven the electrification of powertrain and chassis. To comply with this trend and decrease the bound even further, the present paper proposes the use of hydraulic regenerative shock absorbers for automotive suspension systems. The conversion of linear into angular motion and the suitable control of an integrated electric machine allow to transform part of the vibrational energy into electricity. In these damping devices, the key element is the motor-pump unit that is interfaced onto a conventional hydraulic cylinder architecture. Hence, the proposed research focuses on this component by investigating different design aspects in all the domains of interest. The objective is to optimize the energy conversion efficiency of the unit without affecting its damping control property. To give means of validation, a motor-pump prototype is built and experimentally characterized through a dedicated test rig.

Doubly Salient Dual-PM Linear Machines for Regenerative Shock Absorbers

In order to fully utilize the high-energy nature of permanent magnet (PM) material, the stator-PM structure and the mover-PM structure of linear machines are integrated into one doubly salient PM machine topology, leading to a new class of doubly salient dual-PM linear machines. In essence, PMs are mounted on both the stator and mover iron cores while avoiding magnetic saturation, hence offering the high force density and high power density. Meanwhile, it consists of a fault-tolerant tooth stator and a consequent-pole mover, which can provide the fault-tolerant capability and exert the salient effect, respectively. By using finite-element analysis, the proposed machine is optimized for application to regenerative shock absorbers which can provide on-board renewable energy harvesting in vehicles. The machine performances are analyzed and quantitatively compared with that of its counterparts including the stator-PM linear machine and the mover-PM linear machine. Moreover, both the flat and tubular morphologies of the proposed machine are quantitatively compared and discussed.

Evaluation of ability to regenerate oscillation energy by the suspension system of a two-axle truck

One of the challenges that currently face manufacturers of electric vehicles is the development of an effective energy source. Currently, the main independent source of energy of electric vehicle is an electric traction battery of chemical type, but due to its low intensity, it cannot provide long mileage without recharging. The article describes a method of improving vehicles ' energy efficiency through energy recovery oscillations of the suspension system when driving on uneven road surface. To convert the mechanical energy of vibrations into electrical, the leading manufacturers of the world are developing special regenerative shock absorbers. The article describes the design of such absorbers designed by companies Audi and ZF. For quantitative evaluation of vibrational energy that is potentially possible to convert to electric we used a simulation mathematical model of motion of two-axle vehicle on ridges, implemented in the simulation package MATLAB/Simulink. As inputs in the model was used the implementation of random road profiles that were obtained by the method of forming a filter by known from the literature the spectral characteristics of the irregularities for different types of roads. As a result of the mathematical model of computational experiments, it was determined the amount of dissipation in the suspension system energy when the vehicle is moving with different speed on different road types. Also for comparison was determined the energy spent by the vehicle at different speeds on the road with asphalt. The comparison of the obtained energy values allows to make a conclusion about prospects of application of energy recovery oscillations of the suspension system especially for vehicles capable of high speeds on dirt roads.

A high-efficiency energy regenerative shock absorber using supercapacitors for renewable energy applications in range extended electric vehicle

The energy source of vehicles is changing rapidly and significantly in recent years with the increase in renewable energy technologies especially in the case of electric vehicles (EVs). A smart solution has emerged in which the wasted energy in a vehicle’s shock absorber is converted to an alternative energy for the cars themselves, and this is called an energy regenerative shock absorber. Whereas existing regenerative shock absorbers mainly focus on the methods of energy harvesting, there is no such regenerative shock absorber for use in extended range EVs. In this paper, we present a novel high-efficiency energy regenerative shock absorber using supercapacitors that is applied to extend the battery endurance of an EV. A renewable energy application scheme using regenerative shock absorbers for range extended EVs is designed and proposed for the first time. This system collects the wasted suspension power from the moving vehicle by replacing the conventional shock absorbers as these energies are normally dissipated through friction and heat. The proposed system consists of four main components: the vibration of the suspension input module, transmission module, generator module and power storage module. The suspension vibration induced by the road roughness acts as the system excitation to the energy regenerative shock absorber. The vibration is then transmitted through the mechanical transmission module, which changes bidirectional vibration into unidirectional rotation based on gears and a rack to drive the generator module. The power storage module stores the regenerative energy of the shock absorber in the supercapacitor, which is applied to the EV to improve the cruising mileage. Higher efficiency up to 54.98% at most and 44.24% on average were achieved in the simulation and bench tests is proof that the energy regenerative shock absorber is beneficial and promising in generating energy used for renewable energy applications in extended range EVs.

Energy-harvesting shock absorber with a mechanical motion rectifier

Energy-harvesting shock absorbers are able to recover the energy otherwise dissipated in the suspension vibration while simultaneously suppressing the vibration induced by road roughness. They 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 the 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 oscillatory vibration into unidirectional rotation of the generator. An implementation of a MMR-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 an 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 conventional regenerative shock absorbers in oscillatory motion. Furthermore, road tests are done to demonstrate the feasibility of the MMR shock absorber, in which more than 15 Watts of electricity is harvested while driving at 15 mph on a smooth paved road. The MMR-based design can also be used for other applications of vibration energy harvesting, such as from tall buildings or long bridges.