Controllable seat damper system and control method therefor
AssigneeLord Corporation
InventorDavid M. Catanzarite
Life of this patent
Estimating the term…
Abstract
A controllable fluid damper is employed in a seat suspension system. A microprocessor receives successive signals from a displacement sensor and computes a rate of displacement. This displacement rate is used to determine an appropriate control signal for the damper to provide the desired isolation of the seat occupant from the vibration input to the frame. A rate control method is disclosed as a preferred control technique for providing the desired isolation, although both the control hardware and method can be used independently.
Claims20
A controllable seat damper system for damping vibrations transmitted from a vehicle frame to a vehicle seat, said seat having a seat suspension including a support means and spring means to mount said seat on said frame, said controllable seat damper system comprising components
- a) a controllable damper interconnected between said seat and said frame in parallel with said seat suspension, said controllable damper including a magneto-rheological fluid whose rheological properties can be changed by subjecting said fluid to a magnetic field which has variable strength in order to adjust a force output setting of said controllable damper continuously over a first desired range;
- b) a single primary sensor connected to a portion of said seat suspension for monitoring a position of said seat;
- c) an electronic controller for receiving a signal from said single primary sensor, said electronic controller introducing a control algorithm based solely on said signal from said single primary sensor to calculate an appropriate control signal to send to said controllable damper to adjust a strength of said magnetic field over a second particular range altering said rheological properties thereby changing said force output setting by said controllable damper over said first defined range;
- d) a wiring harness interconnecting said sensor, said controller and said controllable damper with each other and at least one of said components with a power source thereby enabling current and data signals to be transmitted to and between the components, respectively.
A rate-control method of controlling a controllable damper system, said method comprising the steps of
- a) sensing a first displacement of said damper system;
- b) feeding said first displacement to a controller;
- c) sensing a subsequent displacement of said damper system;
- d) feeding said subsequent displacement to said controller;
- e) processing said first and subsequent displacements through a filter within said controller to determine a displacement rate of said damper system;
- f) determining whether said displacement rate is positive or negative;
- g) setting an input gain to a desired extension gain if said rate is positive and to a desired compression gain if said rate is negative;
- h) deriving an output signal equal to said displacement rate if positive and equal to an absolute value of said displacement rate if negative;
- i) comparing said output signal to a preset null band to determine if said signal falls within said null band;
- j) setting an output control signal to a minimum value if said output signal is within said null band and multiplying said output signal by the appropriate gain set in step g) if it is not;
- k) feeding said output control signal to a controllable damper to adjust its force output setting to an appropriate value.
A rate-control method of controlling a controllable seat damper system, said method comprising the steps of
- a) sensing a first displacement of a seat;
- b) feeding said first displacement to a controller;
- c) sensing a subsequent displacement of said seat;
- d) feeding said subsequent displacement to said controller;
- e) processing said first and subsequent displacements through a filter within said controller to determine a displacement rate of said seat;
- f) determining whether said displacement rate is positive or negative;
- g) setting an input gain to a desired extension gain if said rate is positive and to a desired compression gain if said rate is negative;
- h) deriving an output signal equal to said displacement rate if positive and equal to an absolute value of said displacement rate if negative;
- i) comparing said output signal to a preset null band to determine if said signal falls within said null band;
- j) setting an output control signal to a minimum value if said output signal is within said null band;
- k) if said output signal is not within said null band, determining if said displacement of said damper is at an end stop limit;
- l) if so, multiplying said output signal by a preset end stop gain to produce an output control signal;
- m) if said output signal is not at said end stop limit, multiplying said output signal by the appropriate gain set in step g) to produce an output control signal;
- n) feeding said output control signal created during step j), l) or m) to a controllable damper to adjust its force output setting to an appropriate value to damp an induced movement of said seat.
Dependencies are inferred from the claim text.