Patent GB-1283162-A (GB)
Title: Motor control mechanism
IPC: B66B1/52
Filed: 1970-04-17
Abstract: 1283162 Lift control systems WESTING- HOUSE ELECTRIC CORP 17 April 1970 [21 April 1969] 18393/70 Heading B8L [Also in Division G3] When a lift-car is at rest at a first floor, a helical carriage 47, which represents movement of the car is positioned with floor stop e.g. 109A between extended pawls 151, 153 on control head 65 which is in the vertical position. Cam 215 actuates switch 221 to indicate that the car is level with the floor. Cam 71 is positioned so that potentiometer 83 generates a zero pattern signal. In addition, clutch coils 112, 113 are deenergized whereby gear 59 does not engage plate 61. When a car call is registered for the third floor, clutch coils 112, 113 attract armature 115 so forcing pin 121 against a key to engage the gear 59 with the plate 61. Coils are energized to lift pawls 151, 153 clear of the floor stops for the first floor. As the car begins to move, a drive tape 9 rotates a sprocket 11 so that shaft 35 turns the gear 55 and carriage 47, the gear 59 being turned in the opposite direction. Nut 87 engages shaft 49, the carriage 47 being advanced to the right, while the arm 63 rotates the control head 65, and cam 71 adjusts the potentiometer 83 to provide a smoothly increasing reference signal for upward travel, the switch 221 being opened. Initial movement of the control head with respect to the floor stop causes a floor selector to notch to the second-floor position. Continued movement of the car rotates the control head to increase the speed reference signal as the cam 71 is rotated. When the control head approaches the horizontal position, the cam 217 actuates switch 227 to de-energize the clutch-coils 112, 113. Further rotation of the control head is restrained when the control arm engages a stop 231. Spring arm 179 engages bar 237 to prevent pawl 151 from being extended. With the control head in the horizontal position, the potentiometer 83 remains stationary and provides the maximum reference signal for the up direction. As the car approaches the second floor, the floor stop 109B passes under the control head and the floor selector is advanced to the third-floor position. A stop signal is generated as the car approaches the third floor, the floor stop striking the extended pawl 153, and pushing the control head in front of it, the clutch mechanism being prevented from engagement when the control head is pawled. As the control head is rotated in synchronism with the carriage 47 the cam 71 is turned whereby the potentiometer 83 is returned smoothly to the neutral position. As the control head approaches the vertical position, cam 217 actuates switch 223 to initiate opening of the car doors. Cam 215 then actuates the switch 221. To prevent the car from approaching the top of the hatchway at excessive speed, stop 111 strikes the control head 65 and returns it to a vertical position. To provide the same protection at the bottom, pins 243, 245, engage so that plate 61 turns the control arm. In a modification, the potentiometer is replaced by a reactor, a cam varying the reluctance of the magnetic circuit in accordance with the position of the shaft 49, Fig. 12 (not shown). In another embodiment, the cam 71 is associated with push rods adapted to displace a transducer armature and so vary the coupling between windings of a transformer providing a control signal. A drag magnet co-operates with a disc which moves in synchronism with the car and tends to displace the transducer armature in the opposite direction, Figs. 13-15 (not shown). The pattern signal may be compared with a tachometer signal representing the speed of the lift-motor. The resultant signal is amplified by a silicon controlled amplifier and serves as the excitation signal of a Ward Leonard generator.