Abstract: A magnetorheological piston includes a body having a substantially magnetically energizable passageway and a substantially magnetically non-energizable passageway. The substantially magnetically non-energizable passageway has a valveless passageway throat and has a flow cross-sectional area which has a minimum at the passageway throat and which is larger away from the passageway throat. A magnetorheological damper includes a cylinder and the above-described magnetorheological piston, wherein the piston is positioned in, and slideably engages, the cylinder.

Abstract: A magneto-rheological (“MR”) damper having a damper body tube containing an MR fluid. A piston assembly is disposed in the damper body tube and forms an annular flow gap between the piston assembly and the damper body tube. The piston assembly has a piston core containing ferrous material and an electromagnetic coil mounted on the piston core for generating a magnetic field. The damper further includes a ferromagnetic member positioned outside of the damper body tube substantially adjacent the piston assembly for providing at least a part of a magnetic flux return path for the magnetic field.

Abstract: A piston rod for use in a magnetorheological dampening device having a surface finish that renders the device resistant to wear at the elastomeric seal/piston rod interface. The piston rod has a surface finish of Ra<0.065 &mgr;m and &Dgr;a≦1.4°, as measured using a Gaussian filter with a 0.08 mm cut-off length. There is further provided a method of achieving the surface finish, including rotating the piston rod while moving an abrasive tape against the outer surface of the rod.

Abstract: A piston assembly for use with an MR fluid damper. The piston assembly has a piston core and a flux ring positioned in a desired alignment with the piston core so that the flux ring forms an annular flow gap the piston core. The flux ring is secured to the piston core in the desired alignment by a plurality of projections extending across the flow gap between an inner surface of the flux ring and an outer surface of the piston core. The projections are molded through flux ring holes intersecting the inner and outer surfaces of the flux ring. A method for making the piston assembly is also described and claimed.

Abstract: An improved magneto-rheological (“MR”) fluid damper includes a damper cylinder containing a volume of MR fluid. The cylinder includes an inner surface. A piston assembly is disposed in the cylinder and has an outer surface in slidable contact with the cylinder inner surface. The piston assembly includes a flow gap formed thereabout and an external coil surrounding a portion of the cylinder, the external coil capable of generating a magnetic field across at least a portion of the flow gap.

Abstract: A piston rod for use in a magnetorheological dampening device having a surface finish that renders the device resistant to wear at the elastomeric seal/piston rod interface. The piston rod has a surface finish of Ra<0.065 &mgr;m and &Dgr;a≦1.4°, as measured using a Gaussian filter with a 0.08 mm cut-off length. There is further provided a method of achieving the surface finish, including rotating the piston rod while moving an abrasive tape against the outer surface of the rod.

Abstract: A damper body for a magnetorheological (MR) damper and associated methods of forming the damper body. The damper body is formed of a base material, such as a steel, and is coated with an abrasion-resistant layer comprising chromium. The layer of chromium provides a sliding wear surface for sliding contact with a reciprocating piston. To avoid high-stress abrasive wear over the expected service life of the magnetorheological damper, the layer of chromium has a minimum thickness greater than or equal to a minimum thickness of about 8 &mgr;m. In other embodiments, before applying the abrasion-resistant layer of chromium, the damper body is coated with a layer of a hard coating material having a hardness greater than the hardness of the base material. The effective hardness of the damper body is a composite of the respective hardnesses of the base material comprising the damper body and the layer of hard coating material.

Abstract: An improved magnetorheological fluid damper is provided which effectively provides a smooth transition, without a sharp break in the damper force/velocity curve, between very low damping forces near zero damper velocity to higher damping forces at higher piston velocities while maintaining desirable maximum force levels. The damper includes a piston assembly, including a magnet assembly and a flow gap extending through the piston assembly to permit fluid flow between the chambers. The force/velocity optimization feature includes at least one groove open to the flow gap, formed in a non-magnetic portion of the piston and positioned in series with a part of the flow gap in a magnetic circuit generated by the magnet assembly and dimensioned/sized to permit fluid flowing the passage to experience a magnetorheological effect less than a magnetorheological effect experienced by fluid flowing through the flow gap but not through the groove.

Abstract: A magneto-rheological damping device comprises a core element for carrying a magnetic flux and a magnetic flux generator positioned adjacent to a portion of the core element and operable to generate a magnetic flux in the core element. A sleeve is positioned over the core element and magnetic flux generator and includes a plurality of protrusions extending generally radially outwardly from a center of the core element. A flux ring surrounds the core element and sleeve and defining a passage between flux ring and core element for the flow of a magneto-rheological fluid. The sleeve protrusions are configured to engage the flux ring and secure the flux ring in a concentric position around the core element and sleeve.

Abstract: A vehicle suspension damper assembly is provided which includes a cup member with a threaded opening formed therein. A piston rod includes a threaded portion, which is engaged in the threaded opening. An electrical connector including a terminal portion is received in an opening formed in the piston rod. The threaded engagement between the piston rod and the cup member is a predetermined length that reduces deflection of the cup member to reduce transfer of load to the terminal portion of the electrical connector.

Abstract: A vehicle suspension damper assembly is provided which includes a cup member with a threaded opening formed therein. A piston rod includes a threaded portion, which is engaged in the threaded opening. An electrical connector including a terminal portion is received in an opening formed in the piston rod. The threaded engagement between the piston rod and the cup member is a predetermined length that reduces deflection of the cup member to reduce transfer of load to the terminal portion of the electrical connector.

Abstract: A magneto-rheological damping device comprises a core element for carrying a magnetic flux and a magnetic flux generator positioned adjacent to a portion of the core element and operable to generate a magnetic flux in the core element. A sleeve is positioned over the core element and magnetic flux generator and includes a plurality of protrusions extending generally radially outwardly from a center of the core element. A flux ring surrounds the core element and sleeve and defining a passage between flux ring and core element for the flow of a magneto-rheological fluid. The sleeve protrusions are configured to engage the flux ring and secure the flux ring in a concentric position around the core element and sleeve.

Abstract: A piston assembly for use with an MR fluid damper. The piston assembly has a piston core and a flux ring positioned in a desired alignment with the piston core so that the flux ring forms an annular flow gap the piston core. The flux ring is secured to the piston core in the desired alignment by a plurality of projections extending across the flow gap between an inner surface of the flux ring and an outer surface of the piston core. The projections are molded through flux ring holes intersecting the inner and outer surfaces of the flux ring. A method for making the piston assembly is also described and claimed.

Abstract: A magneto-rheological (“MR”) damper having a damper body tube containing an MR fluid. A piston assembly is disposed in the damper body tube and forms an annular flow gap between the piston assembly and the damper body tube. The piston assembly has a piston core containing ferrous material and an electromagnetic coil mounted on the piston core for generating a magnetic field. The damper further includes a ferromagnetic member positioned outside of the damper body tube substantially adjacent the piston assembly for providing at least a part of a magnetic flux return path for the magnetic field.

Abstract: An MR fluid damper having a damper body tube containing a volume of MR fluid. A piston assembly is disposed in the damper body tube to form a flow gap between an outer surface of the piston and an inner surface of the damper body tube. An external coil surrounds a portion of the damper body tube. The external coil is capable of generating a magnetic field across at least a portion of the flow gap. In another aspect, the piston assembly includes a bearing in contact with the, inner surface of the damper body tube. The bearing maintains the piston assembly concentric within the damper body tube while permitting a flow of the MR fluid through the flow gap.

Abstract: A monotube damper and suspension spring assembly for a motor vehicle includes a tubular housing defining a chamber filled with damping fluid. A piston and piston rod reciprocate within the chamber. In order to compensate for volumetric changes of the chamber due to extension and retraction of the piston rod within the chamber, either the upper seal cover or lower bottom ring assembly is slidable within the housing. A preload is applied either to the housing or to the seal cover to thereby bias these elements to compensate for volumetric changes in the chamber.

Abstract: An MR fluid damper having an annular flux ring assembly surrounding a piston core piston assembly which is disposed for reciprocal movement in a cylinder. The flux ring assembly has first and second ferromagnetic flux rings forming opposite ends of the flux ring assembly, and a nonmagnetic annular spacer interposed between the ferromagnetic flux rings. The annular spacer has a plurality of first projecting members extending between the piston core and the flux ring assembly. The plurality of projecting members align the piston core concentrically with respect to the flux ring assembly to form an annular, first flow path between the piston core and the annular flux ring. In an alternative embodiment, the annular spacer has a plurality of second projecting members extending between the flux ring assembly and the cylinder. The second projecting members align the flux ring assembly concentrically with respect to the cylinder, thereby forming an annular, second flow path between the flux ring and the cylinder.

Abstract: An improved magnetorheological fluid damper is provided which effectively provides a smooth transition, without a sharp break in the damper force/velocity curve, between very low damping forces near zero damper velocity to higher damping forces at higher piston velocities while maintaining desirable maximum force levels. The damper includes a piston assembly, including a magnet assembly and a flow gap extending through the piston assembly to permit fluid flow between the chambers. The force/velocity optimization feature includes at least one groove open to the flow gap, formed in a non-magnetic portion of the piston and positioned in series with a part of the flow gap in a magnetic circuit generated by the magnet assembly and dimensioned/sized to permit fluid flowing the passage to experience a magnetorheological effect less than a magnetorheological effect experienced by fluid flowing through the flow gap but not through the groove.

Abstract: An improved magnetorheological fluid damper is provided which effectively provides a smooth transition, without a sharp break in the damper force/velocity curve, between very low damping forces near zero damper velocity to higher damping forces at higher piston velocities while maintaining desirable maximum force levels. The damper includes a piston assembly, including a magnet assembly and a flow gap extending through the piston assembly to permit fluid flow between the chambers. The force/velocity optimization feature includes a groove or passage open to the flow gap, positioned in series with a part of the flow gap in a magnetic circuit generated by the magnet assembly and dimnensioned/sized to permit fluid flowing through the passage to experience a magnetorheological effect less than a magnetorheological effect experienced by fluid flowing through the flow gap but not through the groove. Preferably, the passage is formed in an inner annular surface of a flux ring positioned around a piston core.

Abstract: A novel and improved magnetorheological fluid damper is provided which effectively secures a flux ring to a piston core in a manner which prevents relative axial and radial movement between the flux ring and the core throughout operation while minimizing the size of the piston assembly yet providing effective damping. Several connector devices are disclosed for both axially and radially securing the flux ring relative to the piston core at one end of the piston assembly in a simple manner without increasing the length of the piston assembly. The connector device may include an outer portion brazed to the flux ring, an inner portion connected to the piston core, bridge portions extending between the outer and inner portions, flow passages formed between the bridge portions and an inlet cavity formed adjacent an annular flow gap to permit unimpeded, enhanced laminar flow through the flow gap by improving the damping effect.