| 摘要 |
A controlled member is movable between two end positions defined by respective first and second stops, particularly a flap-type valve member located in the exhaust gas conduit of an internal combustion engine movable between first and second end positions in which the valve member comes into abutment with respective first and second seating surfaces of the conduit. An arrangement for positioning the controlled member includes a drive motor having a motor shaft, a worm screw connected to and driven by the motor shaft, a worm gear meshing with and driven by the worm screw, a positioning-arrangement output shaft coupled to and driving the controlled member, a claw coupling having a first part coupled to and driving the output shaft and a second part coupled to and driven by the worm gear, a unit automatically operative for turning off the drive motor when the controlled member is moved into one of the end positions thereof, and a damping spring arrangement intermediate the two parts of the claw coupling and operative upon drive motor turn-off for absorbing the kinetic energy present in the moving parts of the positioning arrangement to effect braking of such moving parts and so dimensioned as not to be deformed during such absorbing beyond a predetermined maximum permissible extent.
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