World-first energy-recovering suspension from ZF
BY DANIEL GARDNER | 2nd Sep 2013
The GenShock system can recover energy from the movement of a vehicle’s suspension system, which would normally be wasted by conventional systems, thereby saving energy and improving fuel efficiency.
Active suspension is not new to vehicle technology, but existing systems consume energy when operating the integral actuators and pumps necessary to alter chassis settings.
In addition to the various consumers in an active suspension layout, the energy required to move the suspension during normal driving is converted to heat by dampers and lost to the surrounding air in much the same way a brake disc disposes of energy.
ZF claims that by replacing the four conventional dampers with a central hydraulic system, the GenShock system not only offers all the advantages of an active system but also reclaims energy.
Under certain circumstances a hydraulic pump alters the damper conditions for optimum handling characteristics, but at other times the pump behaves in reverse – as a generator – and recovers energy from the moving suspension.
This energy can then be fed back in to the power supply rather than being wasted as heat: theoretically a boon for EV and hybrid vehicle-makers looking for another way to conserve energy.
The principle can be likened to some electric vehicles, which use an electric motor to accelerate but then reverse the role of the motor to when slowing down to regenerate electricity. Re-generative brakes and flywheels are also used in some vehicles.
Not only will the system reduce the amount of energy wasted by a vehicle, ZF also says the system will offer the benefits of an active suspension system with “luxury car comfort levels, and sportscar handling characteristics”.
In addition to efficiency gains, a suspension system which uses energy recovery methods is less likely to overheat under extreme environmental and operational conditions than one which relies on heat dissipation.
Energy recovery is optimal when the suspension is working hardest such as on uneven or bumpy surfaces.
The design requires a control system that can monitor the various sensors up to 10,000 times per second, but despite the advanced technology, ZF claims the system is simple and inexpensive.
Regenerative suspension systems are not just limited to road car use and ZF is currently developing GenShock for trucks, off-road and military applications.
The GenShock system is based on its current non-regenerative active technology, which was introduced in 1994, and is already used by many major car manufacturers worldwide.
