Regenerative shock absorber
Encyclopedia
A regenerative shock absorber is a type of shock absorber
that converts parasitic intermittent linear motion
and vibration
into useful energy
, such as electricity
. Conventional shock absorbers simply dissipate this energy as heat
.
When used in an electric vehicle
or hybrid electric vehicle
the electricity generated by the shock absorber can be diverted to its powertrain to increase battery life. In non-electric vehicles the electricity can be used to power accessories such as air conditioning
. Several different systems have been developed recently, though they are still in stages of development and not installed on production vehicles.
/generator consisting of a stack of permanent magnets and coils to generate electricity. This system was further developed at Tufts University
and has been licensed to Electric Truck, LLC. Preliminary data suggests 20% to 70% of the energy normally lost in the suspension can be recaptured with this system.
coupled to a generator
. The system is controlled by active electronics which optimize damping, which the inventors claim also results in a smoother ride compared to a conventional suspension. They calculate that a large company like Wal-mart
could save $13 million annually by converting their trucks.
Another system has been developed by a team at New York State University. The team consisted of Lei Zuo, Brian Scully, Jurgen Shestani, and Yu Zhou.
Shock absorber
A shock absorber is a mechanical device designed to smooth out or damp shock impulse, and dissipate kinetic energy. It is a type of dashpot.-Nomenclature:...
that converts parasitic intermittent linear motion
Linear motion
Linear motion is motion along a straight line, and can therefore be described mathematically using only one spatial dimension. The linear motion can be of two types: uniform linear motion, with constant velocity or zero acceleration; non uniform linear motion, with variable velocity or non-zero...
and vibration
Vibration
Vibration refers to mechanical oscillations about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.Vibration is occasionally "desirable"...
into useful energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
, such as electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
. Conventional shock absorbers simply dissipate this energy as heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...
.
When used in an electric vehicle
Electric vehicle
An electric vehicle , also referred to as an electric drive vehicle, uses one or more electric motors or traction motors for propulsion...
or hybrid electric vehicle
Hybrid electric vehicle
A hybrid electric vehicle is a type of hybrid vehicle and electric vehicle which combines a conventional internal combustion engine propulsion system with an electric propulsion system. The presence of the electric powertrain is intended to achieve either better fuel economy than a conventional...
the electricity generated by the shock absorber can be diverted to its powertrain to increase battery life. In non-electric vehicles the electricity can be used to power accessories such as air conditioning
Air conditioning
An air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...
. Several different systems have been developed recently, though they are still in stages of development and not installed on production vehicles.
Electromagnetic
A patent for such a device was filed in 2005. This type of system uses a linear motorLinear motor
A linear motor is an electric motor that has had its stator and rotor "unrolled" so that instead of producing a torque it produces a linear force along its length...
/generator consisting of a stack of permanent magnets and coils to generate electricity. This system was further developed at Tufts University
Tufts University
Tufts University is a private research university located in Medford/Somerville, near Boston, Massachusetts. It is organized into ten schools, including two undergraduate programs and eight graduate divisions, on four campuses in Massachusetts and on the eastern border of France...
and has been licensed to Electric Truck, LLC. Preliminary data suggests 20% to 70% of the energy normally lost in the suspension can be recaptured with this system.
Hydraulic
A system developed at MIT uses hydraulic pistons to force fluid through a turbineTurbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
coupled to a generator
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...
. The system is controlled by active electronics which optimize damping, which the inventors claim also results in a smoother ride compared to a conventional suspension. They calculate that a large company like Wal-mart
Wal-Mart
Wal-Mart Stores, Inc. , branded as Walmart since 2008 and Wal-Mart before then, is an American public multinational corporation that runs chains of large discount department stores and warehouse stores. The company is the world's 18th largest public corporation, according to the Forbes Global 2000...
could save $13 million annually by converting their trucks.
Another system has been developed by a team at New York State University. The team consisted of Lei Zuo, Brian Scully, Jurgen Shestani, and Yu Zhou.