22-07-2014, 12:47 PM
A Review on Energy-Regenerative Suspension Systems for Vehicles
A Review on Energy.pdf (Size: 664.64 KB / Downloads: 191)
Abstract
The conventional vehicle suspension dissipates the
mechanical vibration energy in the form of heat which waste
considerable energy. The regenerative suspensions have
attracted much attention in recent years for the improvement of
vibration attenuating performance as well as the reduction of
energy dissipation. Above all, the amount of energy dissipation
and the potential of energy regeneration are discussed, then the
research and development of regenerative suspension is
reviewed, and the energy harvesting schemes and their
characteristics are summarized and remarked. In conclusion,
only combining vibration reducing performance and energy
harvesting efficiency can the regenerative suspensions have a
promising prospect.
INTRODUCTION
HE function of vehicle suspension system is to support
the weight of vehicle body, to isolate the vehicle chassis
from road disturbances, and to enable the wheels to hold the
road surface. Two chief elements in suspension are spring
and damper. Conventionally, damper is designed to dissipate
vibration energy into heat to attenuate the vibration which is
transmitted from road excitation. However, the dissipated
heat is from fuel or electrical power. It is a pity that so much
energy is wasted.
Green manufacturing, also called environmentally
conscious manufacturing, is one of the most popular topics
nowadays. The future of green manufacturing technology is
foreseeable, especially on vehicle industry. Since the
suspension is an important source of energy dissipation, it is
feasible to harvest its vibration energy and convert into
regenerative energy to improve the vehicle fuel efficiency.
Therefore, so called regenerative suspensions arise as the
times require. Instead of dissipating the vibration energy into
heat wastes, the damper in regenerative suspension will
transform the kinetic energy into electricity or other potential
energy and store it for late use. The stored energy can be used
to tune the damping force of the damper to improve the
suspension performance or to power vehicle electronics to
increase vehicle fuel efficiency
ENERGY DISSIPATION OF VEHICLE SUSPENSION
In the past, we pay little attention to energy loss of vehicle
suspension. However, how much energy is dissipated by the
shock absorbers of vehicle suspension? According to
reference [1], only 10-20% the fuel energy is used for vehicle
mobility. One of the important losses is the energy
dissipation in suspension vibration. Velinsky et al. [2]
concluded that the dissipated energy by suspension dampers
is related with road roughness, vehicle speed, suspension stiff
and damping coefficient. Segel et al. [3] analyzed the energy
dissipation of dampers of passenger vehicle, and shown that
the total power of four dampers was about 200W when
running on a poor road at the speed of 13.4m/s. These data
indicate that the energy dissipation of vehicle suspension
can’t be ignore
ENERGY HARVEST FROM VEHICLE SUSPENSION
On the other hand, how much energy we may capture from
vehicle suspension? Suda et al. [4] proved that the harvested
energy in the regeneration process is enough to meet the
energy requirement in consumption process for
electromagnetic active suspension, which means the
suspension is self-powered. The estimation by H su [5]
indicated the average regenerative power of each suspension
for GM Impact running on the highway at 16 m/s reached
100W accounting for about 5% of driving power. F. Yu et al.
[6] compared the energy consumption of passive and active
suspension of car. Their simulation, under the conditions that
the vehicle speed was 20m/s, the road roughness was class C,
the simulation time was 20s, indicated that energy
consumption of passive suspension is 651 kJ, while 645 kJ
for active suspension which decreased the RMS of sprung
mass acceleration by 50%. If the suspension vibration energy
can be recycled, the energy consumption of active suspension
will be reduced significantly. Theoretical results show a
maximum of 10 % fuel efficiency can be recovered from
vehicle suspension system by implementing regenerative
shock absorbers [1].
IV. CONFIG
Electromagnetic Regenerative Suspensions
On the contrary, electromagnetic regenerative suspension
transforms the shock energy into electric energy that is more
convenient to store and reuse, and has high performance,
increased efficiency, less space requirements, and so on [10].
In recent years, electromagnetic suspension (EMS) system
has drawn worldwide attention. Permanent magnets motor is
favored in EMS to provide active force in actuator mode or
damping force in generator mode. The damping force can be
simply changed by tuning the shunt resistances. There are six
types of electromagnetic regenerative suspension classified
by structure configuration, and relating researches will be
stated as follow
Hydraulic Transmission Electromagnetic Suspensio
Levant Power Corp. [28] is developing a regenerative
damper, called GenShock, combining hydraulic transmission
and electric motor. Fig.5 shows the working principle of this
damper. A suit of rectifying pipe guarantees that the
hydraulic motor driven by fluid rotates by a consistent
direction whatever the piston runs up or down. Because the
rotation direction of electric motor doesn’t alternate
frequently, the regenerative efficiency is enhanced obviously
Conflict
The primary purpose of improving suspension
performance is to better ride comfort and handling stability,
such as active suspension, semi-active suspension. Active
suspension owns the best vibration control performance, but
must consume lots of energy, while the actuator just works as
passive or semi-active damper in regeneration process,
whose control performance is not excellent as that of active
state. So as to saving energy, despite some strategies may be
established to reach the balance between regenerated and
consumed energies, we have to scarify vibration control
performance evidently. Thereby, there is conflict between
regeneration and vibration contro
Efficiency
For regenerative suspension, how to enhance the
efficiency of harvesting energy is very important. For
absence of speed increaser, the direct-drive motor has a low
energy recovering efficiency. However, as to ball screw and
rack-pinion damper, speed increaser leads to more inertia
loss which decreases the regeneration efficiency and
CONCLUSION
Conventionally, the vibration energy of vehicle suspension
is dissipated as heat by shock absorber, which wastes a
considerable number of resources. Regenerative suspensions
bring hope for recycling the wasted energy. All types of
regenerative suspension, especially electromagnetic
suspension, and their properties are reviewed in this paper.
From the perspective of comprehensive performance
including vibration control ability, regenerative efficiency
and application reliability, the configuration of hydraulic
transmission and self-powered MR damper shows the best
attraction. With improvement of technology, regenerative
suspension may become one of promising trends of vehicle
industry