Magnetorheological piston and damper

#The present invention relates generally to piston dampers, and more particularly to a magnetorheological (MR) piston and damper.

#Conventional piston dampers include MR dampers having a cylinder containing an MR fluid and having an MR piston which slideably engages the cylinder. The MR fluid passes through an orifice of the MR piston. Exposing the MR fluid in the orifice to a varying magnetic field, generated by providing a varying electric current to an electric coil of the MR piston, varies the damping effect of the MR fluid in the orifice providing variably-controlled damping of relative motion between the MR piston and the cylinder. The electric current is varied to accommodate varying operating conditions, as is known to those skilled in the art. A rod has a first end attached to the MR piston and a second end extending outside the cylinder. The cylinder and the rod are attached to separate structures to dampen relative motion of the two structures along the direction of piston travel.

#A known design includes an MR piston having a substantially annular, magnetically energizable passageway and a magnetically non-energizable passageway positioned radially inward from the magnetically energizable passageway. The magnetically non-energizable passageway includes a check valve which is in either a valve closed position or a valve open position. The check valve blocks flow in one direction (usually when the rod moves more outward from the cylinder). The check valve allows flow in the other direction (usually when the rod moves more inward into the cylinder). The flow cross-sectional area of the magnetically non-energizable passageway is chosen for a particular damper application.

#FIG. 1 is a longitudinal cross-sectional view of a portion of a first embodiment of a magnetorheological piston and damper of the invention including a magnetorheological piston body having a longitudinal end plate with a monolithic portion bounding the passageway throat of the substantially magnetically non-energizable passageway;

#FIG. 2 is a longitudinal cross-sectional view of a portion of a second embodiment of a magnetorheological piston and damper of the invention including a magnetorheological piston body having a longitudinal end plate and including an orifice plug;

#FIG. 3 is a longitudinal cross-sectional view of a portion of a third embodiment of a magnetorheological piston and damper of the invention including a magnetorheological piston body having a core with an electrical coil and including an orifice tube;

#Referring now to the drawings, wherein like numerals represent like elements throughout, FIG. 1 shows a first embodiment of the present invention. A first expression of the first embodiment is for a magnetorheological piston 1 10 which is also known as a magnetorheological damper piston. An alternate first expression of the first embodiment is for a magnetorheological damper 112 which includes the magnetorheological piston 110. An application of the magnetorheological damper 112 is its use as a shock absorber for an automobile, an airplane, or other type of vehicle. Another application is use of the magnetorheological damper 112 to provide motion resistance on exercise equipment such as stair climbers and rowing machines. A further application is use of the magnetorheological damper 112 to provide motion isolation for a building, bridge, or other structure subject to earthquakes. An additional application is use of the magnetorheological damper 112 to dampen vibrations encountered by vehicles and structures in outer space. Other applications are left to the artisan.

#In a first expression of the first embodiment of the invention shown in FIG. 1, the magnetorheological piston 110 includes a magnetorheological piston body 114 having a substantially magnetically energizable passageway 116 and having a substantially magnetically non-energizable passageway 118 (also known as a by-pass) spaced apart from the substantially magnetically energizable passageway 116. The term “passageway” means a through passageway. The substantially magnetically non-energizable passageway 118 has a valveless passageway throat 120 and has a flow cross-sectional area which has a minimum at the passageway throat 120 and which is larger away from the passageway throat 120.

#In a first example of the first expression, the magnetorheological piston body 114 has a longitudinal axis 122, the substantially magnetically energizable passageway 116 is substantially coaxially aligned with the longitudinal axis 122, and the substantially magnetically non-energizable passageway 118 is disposed radially inward from the substantially magnetically energizable passageway 116. In one construction, the substantially magnetically energizable passageway 116 is a substantially annularly cylindrical passageway having a flow cross-sectional shape of segments of a substantially circular ring. In the same or a different construction, the substantially magnetically non-energizable passageway 118 is a cylindrical passageway having a flow cross-sectional shape of a circle apart from the passageway throat 120. In the same or a different construction, the passageway throat 120 has a flow cross-sectional shape of a circle, a radially-aligned ellipse, or a circumferential arc segment. Other shapes are left to the artisan.