Method for moving an elevator car of an elevator in order to evacuate passengers, and brake opening device for moving an elevator car of an elevator
A method for moving an elevator car of an elevator to evacuate passengers from the elevator car in the event of a power failure, wherein a brake blocks a vertical movement of the elevator car, includes the following steps: transmitting electrical power to the brake of the elevator to release the brake and enable the vertical movement of the elevator car, the brake being moved and held in a large number of positions, ranging between a fully closed position and a fully opened position, according to the electrical power transmitted; determining an actual speed at which the elevator car is moving; comparing the actual speed with a target speed; and adjusting, in particular increasing or reducing, according to a deviation of the actual speed from the target speed, the electrical power transmitted to the brake, so that the actual speed substantially corresponds to the target speed.
1. A method for moving an elevator car of an elevator to evacuate passengers from the elevator car when a power failure occurs, wherein a brake blocks a vertical movement of the elevator car, the method comprising the steps of:
transmitting electrical power to the brake to release the brake and enable the vertical movement of the elevator car, the brake being adapted to move and be held in a plurality of positions ranging between a fully closed position and a fully open position according to the electrical power transmitted;
determining an actual speed at which the elevator car is moving;
comparing the determined actual speed with a predetermined target speed; and
continuously modulating the transmitted electrical power causing the brake to adjust to the positions between the fully closed position and the fully open position so that the determined actual speed reaches and maintains the target speed.
2. The method according to claim 1 wherein continuously modulating the transmitted electrical power includes modulating a semiconductor switch that connects the brake to an electrical energy source.
3. The method according to claim 2 wherein the semiconductor switch is an insulated-gate bipolar transistor.
4. The method according to claim 1 including transmitting the electrical power to the brake as electrical pulses and modulating the transmitted electrical power by increasing or decreasing at least one of a pulse width, a pulse amplitude and a pulse frequency of the electrical pulses.
5. The method according to claim 4 wherein the electrical pulses are DC voltage pulses.
6. The method according to claim 4 wherein the electrical pulses are rectangular pulses.
7. The method according to claim 1 including starting the method steps in response to actuation of a manual evacuation switch.
8. The method according to claim 1 wherein the method steps of determining, comparing and adjusting are repeated during actuation of a manual evacuation switch.
9. The method according to claim 1 including ending the method steps when the car reaches a floor.
10. The method according to claim 1 including stopping the transmission of the electrical power to the brake when the determined actual speed exceeds a predetermined speed limit thereby causing the brake to close.
11. The method according to claim 1 including stopping the transmission of the electrical power to the brake when the determined actual speed falls below a predetermined speed limit thereby causing the brake to close.
12. A brake opening device for moving an elevator car of an elevator to evacuate passengers from the elevator car when a power failure occurs, wherein a brake blocks a vertical movement of the elevator car, the brake opening device comprising:
an electrical energy source for supplying electrical power to the brake;
a semiconductor switch connecting the brake to the electrical energy source; and
a control device modulating the semiconductor switch to continuously modulate the transmitted electrical power in a closed-loop manner causing the brake to adjust to the positions between the fully closed position and the fully open position so that an actual speed of the elevator car reaches and maintains a target speed.
13. The brake opening device according to claim 12 including a speed determination device determining the actual speed of the elevator car.
14. The brake opening device according to claim 13 wherein the speed determination device includes at least one of an encoder and a magnetic reader on the elevator car reading a magnetic tape in a shaft in which the elevator car is moving.
15. An elevator for moving passengers, the elevator comprising:
an elevator car for receiving the passengers; and
a brake opening device according to claim 12 .