How do electronic suspension systems work?
The basic idea behind simpler electronic
suspensions is to use electronically adjustable shocks and/or struts
so suspension ride control characteristics can be adjusted or adapted
to changing driving conditions, resulting in improved ride and handling.
Electronic shocks and struts have a small
electric actuator motor mounted either atop the unit or inside to rotate
a control rod or selector valve that opens or closes metering orifices
in the piston valve.
This changes the relative stiffness of the
shock as it travels through compression and rebound. The next generation
of electronic shocks will use solenoids rather than motors because solenoids
allow faster response times.
The position of the control rod or selector
valve inside the shock or strut is determined by a dash-mounted switch
in manually controlled systems and/or a microprocessor in systems with
more sophisticated automatic controls.
Electronic shocks are nothing new. The Japanese
introduced them to the U.S. market back in 1983 on the Mazda LX626 and
the Nissan 300ZX. Since then, they have been offered on a variety of
Japanese sports coupes and luxury sedans.
In recent years, systems have been adopted
by numerous domestic models as well. The 1988 Lincoln Continental was
the first domestically-built vehicle to sport electronically adjustable
shocks, followed by the Ford Probe and Corvette in 1989.
One advantage of electronically adjustable
shocks/struts that becomes quickly apparent when you are behind the
wheel is that no one ride control setting is right for all road conditions.
The damper setting that works best depends on the frequency and severity
of the oscillations. A soft setting that gives a boulevard-smooth ride
under one type of driving condition lacks sufficient dampening action
to control the vibrations that are produced under different road conditions.
Conversely, a firm setting may give better
ride control under different driving conditions, but become unacceptably
harsh under others.
The more complicated systems add automatic
load leveling (to compensate for changes in vehicle loading) and/or
ride height adjustment (vehicle lowers at speed to reduce wind resistance).
The most advanced electronic suspension today is the optional
active suspension under the Infinity Q45. It uses hydraulic actuators
instead of conventional or electronic shocks to support a portion of
the vehicle's weight.