Magnetorheological fluid damper tunable for smooth transitions

A damper, comprising:

• a cylinder containing a magnetorheological fluid;
• a piston assembly slidably mounted for reciprocal movement in the cylinder to form a first chamber positioned on one side of the piston assembly and a second chamber positioned on an opposite side of the piston assembly, the piston assembly having a fluid flow passage therethrough defining a flow gap permitting limited fluid flow between the first chamber and the second chamber and a groove adjacent and open to the flow gap along at least a portion of the flow gap in the direction of fluid flow, the piston assembly further including a magnet assembly establishing a magnetic flux circuit through the flow gap and through the groove in series with a region of the flow gap adjacent the groove, the magnetic flux being established through the flow gap and groove transversely to the direction of fluid flow therethrough to cause magnetorheological fluid flowing through the flow gap and the groove to experience a magnetorheological effect affecting the flow of the magnetorheological fluid therethrough, whereby the groove causes the magnetic flux density therethrough to be smoothly reduced from that in the remainder of the flow gap, wherein the flow gap comprises an annular, axially directed passage within the piston assembly and the groove is axially directed along one of an inner wall and an outer wall defining the annular, axially directed passage.

A damper, comprising:

• a cylinder containing a magnetorheological fluid;
• a piston assembly slidably mounted for reciprocal movement in the cylinder to form a first chamber positioned on one side of the piston assembly and a second chamber positioned on an opposite side of the piston assembly, the piston assembly having a fluid flow passage therethrough defining a flow gap permitting limited fluid flow between the first chamber and the second chamber and a groove adjacent and open to the flow gap along at least a portion of the flow gap in the direction of fluid flow, the piston assembly further including a magnet assembly establishing a magnetic flux circuit through the flow gap and through the groove in series with a region of the flow gap adjacent the groove, the magnetic flux being established through the flow gap and groove transversely to the direction of fluid flow therethrough to cause magnetorheological fluid flowing through the flow gap and the groove to experience a magnetorheological effect affecting the flow of the magnetorheological fluid therethrough, whereby the groove causes the magnetic flux density therethrough to be smoothly reduced from that in the remainder of the flow gap, wherein the magnetic flux circuit comprises magnetic poles defining the flow gap and groove and the flow gap and groove in series provide a greater gap width thereacross between the magnetic poles than the flow gap alone.