| 摘要 |
<p>An apparatus for controlling the transmission of torque between drive elements using an electroactive fluid (20) which is sealed within an enclosed chamber (18). A housing (12) defines the chamber (18) and includes at least one end defining an opening (12a). Spaced electrodes (12,16) are provided in the chamber in contact with the fluid (20) and are respectively connected to the drive elements. A controllable power source (34) applies a variable electric field to the fluid (20) such that force is transmitted between the electrodes (12,16) by the fluid according to the strength of the field. A shaft (22) connects one (16) of the electrodes to one of the elements and extends through the opening (12a). A ferrofluid seal assembly (40) prevents leakage of the fluid (20) from the chamber (18) through the opening (12a). The assembly (40) defines with the shaft (22) an annular space in communication with the fluid (20). A magnetic circuit (24,22,42,44) is provided in the assembly by a permanent magnet (44) for applying a concentrated magnetic field in one or more regions across the annular space. A ferrofluid (46) which is immiscible with the electroactive fluid (20) occupies the regions as though it were a liquid O-ring, thus sealing the fluid (20) within the chamber (18) both when the shaft (22) is stationary and when rotating. <IMAGE></p> |
