| 摘要 |
972,415. Electric motor driving arrangements. H. KORTHAUS, and R. WILKE. Feb. 8, 1963 [March 8, 1962], No. 5252/63. Heading H2A. [Also in Division B8] In a screw-and-nut actuator, the rotating nut 11 is driven by an electromagnetically operated clutch in a casing compartment 102 separate from the driving motor 2, and prevented from running back by an electromagnetically operated brake in a further compartment 103. By varying the excitation of the driving clutch the maximum effort of the operating rod 18 may be adjusted. Moreover, the arrangement enables the actuator to be stopped in any position, and the heat generated in the screw is remote from the motor. The magnetic clutch assembly 21, 23 is mounted in a rotatable cage driven from the motor rotor by inter-engaging splines 28a and runs in bearings 20 in the casing partitions on either side of the central compartment 102. The spindle nut 11 is mounted at either end in roller bearings 12 which permit axial movement which operates a cut-out switch when the load resistance reaches a preset value. The clutch consists of an annular electromagnet 21 excited by a coil 23, and acts on iron discs 24, 24a carried by ball bearings on the nut 11 and coupled thereto in opposite directions by freewheel clutches 25, 25a respectively. It is the magnetic adhesion of one or other of these discs to the clutch-pole 23 that determines the limiting thrust that can be applied by the actuator before axial movement of the nut disconnects the drive. In the end compartment 103 there is an electromagnet 30 which is carried by balls 32 in axial grooves 33 so that it can slide axially to follow a brake disc 29 on the nut but cannot rotate. Excitation of this electromagnet enables the actuator to be locked in any position. The brake disc 29 carries a depending skirt 35a which operates the limit switch 35 which serves to switch off the motor and energize the brake when the nut is axially displaced. The clutch and brake surfaces may be toothed for better grip. Alternative forms of permanent and electromagnetic clutch are described (Figs. 2 and 3, not shown) having a single disc mounted on the nut. |
