Magnetorheological fluid-controlled vehicle suspension damper

#The invention relates generally to the field of suspension systems for vehicles. In particular, the invention relates to a magnetorheological fluid actuated damper for use in vehicular suspension systems.

#Suspension systems are used in modern vehicles to tune the characteristics of the ride and handling of the vehicle. The suspension system in each type of vehicle is matched to the type of ride that the operator of that vehicle would prefer. Some vehicles have suspension systems that provide a smoother ride than others and some vehicles have tighter, more precise handling characteristics. More modern suspension systems often allow an operator to choose the type of ride for the vehicle. For example, an operator might desire a “softer” ride when driving over rougher terrain and a “harder” ride with more precise handling when driving on smooth terrain.

#A magnetorheological (“MR”) fluid is a substance that relies on a magnetically capable media compounded in a way that allows the substance to change form from a liquid state to a more viscous state. In one form, an MR fluid has a viscosity and consistency much like common motor oil. When a magnetic field is applied, however, the fluid changes form, becoming more resistant to shear force. This increase in viscosity results from a dipole moment introduced into magnetic particles suspended in the fluid from the magnetic field. The particles form chains, aligning in parallel to the magnetic field. The increase in viscosity depends on the strength of the field applied to the fluid and the size and quantity of the particles. This change in viscosity of the fluid takes place within milliseconds.

#FIG. 1 is a perspective view of an embodiment of the present invention;

#FIG. 2 is a cross-sectional view along line 2—2 in FIG. 1;

#FIG. 3 is a cross-sectional view along line 3—3 in FIG. 1;

#Referring in combination to FIGS. 1-3, a preferred embodiment of the MR-actuated damper 10 of the present invention is shown. First 12 and second 14 cylinders are provided. The second cylinder 14 preferably has a hollow interior that is shaped and sized to be slightly larger than the outer diameter of the first cylinder 12. The first cylinder 12 is positioned inside the hollow interior of the second cylinder 14 such that the first cylinder 12 and the second cylinder 14 are spaced apart from each other.

#The positioning of the first cylinder 12 inside the second cylinder 14 forms a gap 16 between the first 12 and second cylinders 14. This gap 16 is preferably filled with an MR fluid 18. The damper 10 is preferably sealed at a side wall 32 of the second cylinder 14 so that the MR fluid 18 does not leak out of the damper 10. Since the gap 16 is preferably substantially thin, only a small volume of MR fluid 18 is required to fill the entire gap 16. The small MR fluid 18 requirement of the present invention reduces the cost of the damper 10 and also reduces the necessary strength of the seal in the damper 10.

#In the embodiment of the present invention shown in FIGS. 1-3, the second cylinder 14 is preferably attached to the chassis 20 of the vehicle. The preferred mounting method shown in the Figures includes a standard bracket 22 welded to the second cylinder 14 and attached to the chassis 20 by nuts 24 and bolts 26. Other attachment methods are possible. For example, the second cylinder 14 could be attached to the chassis utilizing any method known in the art. The attachment method should prevent any movement or rotation of the second cylinder 14 such that the second cylinder 14 acts as a stator.