Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.
Semi-active suspension systems are greatly expected to be
in the mainstream of future controlled suspensions for
passenger cars. In this study, a continuous variable damper for
a passenger car suspension is developed, which is controlled
actively and exhibits high performance with light weight, low
cost, and low energy consumption. To get a fast response of
the damper, a reverse damping mechanism is adapted, and to
get small pressure change rate after blow-off, a pilot controlled
proportional valve is designed and analyzed. The reverse
continuous variable damper is designed as a HS-SH damper
which offers good body control with reduced transferred input
force from the tire, compared with any other type of suspension
system. The damper structure is designed, so that rebound and
compression damping forces can be tuned independently, of
which the variable valve is placed externally. The rate of
pressure change with respect to the flow rate after blow-off
becomes smooth when the fixed orifice size increases, which
means that the blow-off slope is controllable using the fixed
orifice size. Damping forces are measured with the change of
the solenoid current at the different piston velocities to confirm
the maximum hysteresis of 20 N, linearity, and variance of
damping force. The damping force variance is wide and
continuous, and is controlled by the spool opening, of which
scheme is usually adapted in proportional valves. The reverse
continuous variable damper developed in this study is expected
to be utilized in the semi-active suspension systems in
passenger cars after its performance and simplicity of the
design is confirmed through a real car test.
