Patent GB-439125-A (GB)
Title: Electric operation of lift doors
IPC: B66B13/14
Filed: 1934-05-30
Abstract: 439,125. Operating lift gates. MOLANDER, V., Marian Sairaala, Helsingfors. May 30, 1934, No. 16168. [Class 65 (i)] An electrically-operated lift gate is controlled automatically by operation of the shaft doors, switches operated by the gate and doors being arranged to move the gate to the position corresponding to that of the door when these positions are different, the motor circuit being broken when the door and gate are in correspondence ; a push-button is also provided in the cage for control of the gate. In the arrangement shown, switches U are operated by the shaft doors at the various floors, these switches being operated when their respective doors start moving in either direction, and limit switch S and reversing switch S<2> for the cage gate motor M are operated by the cage gate, but are not actuated until the gate completes its movement in either direction. A push-button P in the cage actuates two contacts H, H<1> with holding electromagnets E, E<1>, the former starting the motor to open the gate while the latter holds open contacts A in the gate-closing circuit until the shaft door is opened to break the circuit at U, so that premature closing of the gate due to delay in opening the door is prevented. Contact H<1> and electromagnet E<1> may be dispensed with, contacts A then being opened by the cage gate or the switch S for a predetermined time to allow the door to be opened. Opening of the gate may also be caused by opening one of the shaft doors to reverse its switch U. When all the shaft doors are closed, the cage gate is automatically closed. With this arrangement, if the button P is pressed while the gate is closing, the closing circuit is opened at A and held open by E<1>, while the opening circuit is open at S, so that the gate stops and cannot be moved by power in either direction until the shaft door has been re-opened and closed to de-energize E', while if the closing of the gate is completed by hand E<1> remains energized ; to avoid these disadvantages, the contacts H, H<1> may be operated by a relay controlled by a push-button in a circuit which is broken when limit switch S is reversed. This arrangement may be modified for automatic control, the control panel in the cage having a separate button for travel to each floor, these buttons operating contacts, with holding electromagnets, being arranged in parallel to take the place of contact H and electromagnet E<1> and to energize the relay operating contact H<1>; a normally-open switch is provided at each floor, for operation by the cage, to prevent completion of the motor circuit until the cage arrives at the floor corresponding to the operated button. In an alternative to this arrangement, the floor switches are replaced by an inertia switch, with holding electromagnets, on the cage, closed when the cage starts or stops, and the push-buttons in parallel control a single stick relay which closes the motor control circuits, with delay action to prevent completion of the circuit when the inertia switch is closed at the starting of the cage. In any of these arrangements, the contacts A, H<1> and holding electromagnet E<1> may be dispensed with; the shaft door switches U are then arranged to be normally open, their left-hand contacts being closed only momentarily when the shaft door is closed and a stick relay being provided to maintain the closing circuit until the cage gate is closed. The arrangement shown in Fig. 7 incorporates this feature, the stick relay being shown at E<5>, and also includes the automatic control arrangement of buttons P, contacts H with holding electromagnets E, and floor contacts Q. This arrangement also includes means to allow closing of the gate by power if it is stopped partly open owing to opening and immediate closing of a shaft door ; the right-hand contacts of switch S are replaced by a separate switch K, which closes as soon as the gate starts to open and energizes a stick relay E<3>, and an additional switch S<1> is coupled to S, the contact of E<3> and switch S<1> completing the circuit of a spring-biassed reversing relay E'. In normal operation, the left-hand contacts of switches U, for closing the gate, are not closed until the gate is fully open and switch S<1> is therefore open to prevent operation of E'. To prevent opening of the gate between floors, in the non-automatic arrangements, a circuit-breaker at each floor, closed by arrival of the cage, or on the cage, closed at each floor, may be provided. The shaft door switches U may be replaced by a switch on the cage. The transmission connecting the motor to the gate may be arranged to reverse the motion of the gate automatically without reversal of the motor, in which case the reversing switch S<2> is unnecessary and the motor always runs in the same direction except when relay E', Fig. 7, comes into action. The contacts in the motor circuits may be operated by relays instead of directly by the door and gate switches.