CNET On Cars - Car Tech 101: Understanding adaptive suspension
CNET On Cars - Car Tech 101: Understanding adaptive suspension
2013-11-11
on this Jaguar XJ for example I've got
drive controls that include a sport mode
a dynamics mode and those speak to the
adaptive suspension which Jags engineers
say allowed them to monitor for almost
900 parameters of the vehicles
relationship with the road and gravity
up from about 80 on a typical dead steel
spring suspension and whether you're
monitoring 80 or 800 parameters of
suspension and vehicle relationship with
the road they're really just four major
technology groups that get that done
there's active pneumo hydraulic this
mouthful uses a combination of pumps and
accumulators to move hydraulic fluid and
compress nitrogen gas to the cars four
corners as needed in milliseconds to
take over the functions of both shock
absorption and sway control it's very
exotic and expensive we've driven it on
the McLaren mp4-12c where it keeps the
car almost oddly level in corners but
also kept the ride compliant then
there's active electromagnetic this
system replaces all that pneumo
hydraulic plumbing and pumping with
linear electric motors at each corner
it's response can be even faster and it
doesn't strew plumbing all over the car
the Bose Company of Audio Fame oddly
enough is well known as an innovator in
this technology and it actually derives
some of the basics from the study of
waves and electro magnetics a lot like
speakers okay that's active now on to
the adaptive or semi active technologies
these are so named because all they do
is react to what the road and the car
are doing they don't actually bring
their own forces to that relationship
first up is adaptive solenoid or
adaptive valve now your typical shot
works by passing hydraulic fluid through
a series of small valves or orifices
which limit the rate that fluid can move
back and forth that limits the movement
of the shock and therefore the movement
up and down of the car adaptive valve or
solenoid tech gives you electronic
control over those shock valves so the
rate at which fluid moves around inside
the shock can be changed on the fly
therefore varying the shocks damping
behavior
that brings us to adaptive
magnetorheological it's a mouthful but
perhaps the fastest-growing adaptive
suspension right now this GM developed
system uses a special kind of shock
fluid with particles suspended in it
that react to electric current and
simply put that makes the fluid present
itself to the mechanism more or less
viscous and that varies the damping
effect in very subtle ways that can be
changed very rapidly and with great
range just by varying the current you
apply to the fluid by the way if you see
a wire coming off a shock absorber like
this here in the center of the shock
tower that's a dead giveaway you've got
adaptive suspension in this case
magnetorheological technology and this
is the current flowing through here now
so far these adaptive suspension systems
have gone in two directions one is for
extremely high performance cars and the
other is for very luxurious high comfort
vehicle applications we're not seeing
these show up in a lot of mainstream
cars yet because they don't have an
everyday efficiency component they're
never going to save you in the mpg or
make the car any less expensive so we're
talking about here is they still mid to
upper class tech if you want to divide
the car market that way but as this
technology comes down in prices of
course it will expect to see it on more
cars in the sub $30,000 class
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