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Motorola is patenting a shock absorber for cars in which motion is damped by
a fluid whose viscosity increases in an electric field. This
“electro-rheological” fluid is sealed in a container between two electrodes that
can apply a potential of thousands of volts, giving the driver push-button
control over the car’s ride-damping on bumpy roads. When the weather is cold,
the fluid becomes more viscous. To compensate for this, Motorola proposes
putting a bimetallic strip inside the cylinder (GB 2 330 891), attached to one
of the electrodes. When the fluid is cold, the strip bends towards the opposite
electrode, allowing some of the charge to leak away. This reduces the voltage,
ensuring that the shock absorber works the same on hot days as it does on cold
days.