Temperature responsive suspension system control

A vehicle suspension system control method comprising the steps of:

• determining ambient temperature;
• setting an initial damping fluid temperature estimation equal to the ambient temperature, and thereafter iteratively
• determining a relative velocity of at least one damper of the suspension system;
• determining, responsive to the relative velocity and the damping fluid temperature estimation, a damper force value;
• estimating heat input to the damper responsive to the relative velocity and the damper force value;
• estimating heat outflow from the damper responsive to the estimated damper fluid temperature and the ambient temperature;
• determining a change in temperature of the damping fluid responsive to the estimated heat input and the estimated heat outflow;
• updating the estimated damper temperature responsive to the estimated damper fluid change in temperature;
• and
• if the estimated damping fluid temperature is not above a predetermined threshold, constraining a damper actuator command to a predetermined maximum value for cold temperature operation of the damper to minimize occurrence of suspension noise and harshness during cold temperature vehicle operation.

A method of indicating cold temperature operation of a suspension system damper, comprising the steps of:

• measuring an ambient temperature outside a vehicle;
• measuring a relative velocity of a suspension system damper;
• responsive to the relative velocity and the ambient temperature, estimating a damping fluid temperature of damping fluid within the damper;
• comparing the estimated damping fluid temperature to a predetermined threshold;
• wherein an estimated damping fluid temperature below the predetermined threshold indicates cold temperature operation of the damper.

A method of indicating cold temperature operation of a suspension system damper comprising the steps of:

• determining ambient temperature;
• setting an initial damping fluid temperature estimation equal to the ambient temperature, and thereafter iteratively
• determining a relative velocity of at least one damper of the suspension system;
• determining, responsive to the relative velocity and the damping fluid temperature estimation, a damper force value;
• estimating a heat input to the damper responsive to the relative velocity and the damper force value;
• estimating a heat outflow from the damper responsive to the estimated damper fluid temperature and the ambient temperature;
• determining a change in temperature of the damping fluid responsive to the estimated heat input and the estimated heat outflow;
• updating the estimated damper temperature responsive to the estimated damper fluid change in temperature;
• and
• if the estimated damping fluid temperature is not above a predetermined threshold, indicating cold temperature operation of the damper.

A controllable suspension system comprising:

• means for sensing ambient temperature;
• a controllable variable force damper with a piston and a cylinder, wherein the controllable variable force damper is responsive to a damper command;
• means for determining a relative velocity of the piston and cylinder of the variable force damper;
• a microcomputer controller comprising means, responsive to the relative velocity and the ambient temperature, for estimating a damping fluid temperature of damping fluid within the damper, means for comparing the estimated damping fluid temperature to a predetermined threshold and means for indicating a cold temperature operation of the damper if the estimated damping fluid temperature is not above the predetermined threshold.