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

Abstract

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.

Claims

1-15. (canceled)

16. 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 steplessly adjusting the transmitted electrical power in response to a deviation of the determined actual speed from the target speed such that the determined actual speed corresponds to the target speed.

17. The method according to claim 16 including adjusting the transmitted electrical power by modulating a semiconductor switch that connects the brake to an electrical energy source.

18. The method according to claim 17 wherein the semiconductor switch is an insulated-gate bipolar transistor.

19. The method according to claim 16 including transmitting the electrical power to the brake as electrical pulses and adjusting 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.

20. The method according to claim 19 wherein the electrical pulses are DC voltage pulses.

21. The method according to claim 19 wherein the electrical pulses are rectangular pulses.

22. The method according to claim 16 including starting the method steps in response to actuation of a manual evacuation switch.

23. The method according to claim 16 wherein the method steps of determining, comparing and adjusting are repeated during actuation of a manual evacuation switch.

24. The method according to claim 16 including ending the method steps when the car reaches a floor.

25. The method according to claim 16 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.

26. The method according to claim 16 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.

27. 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 steplessly control the electrical power supplied to the brake in a closed-loop manner to bring the brake into and hold the brake in a plurality of positions.

28. The brake opening device according to claim 27 including a speed determination device determining a speed of the elevator car.

29. The brake opening device according to claim 28 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.

30. An elevator for moving passengers, the elevator comprising: an elevator car for receiving the passengers; and a brake opening device according to claim 27.

31. A method of using a semiconductor switch, the method comprising the step of: operating the semiconductor switch to modulate a voltage applied to an elevator brake of an elevator car such that the elevator car is moved at a constant speed during an evacuation operation.

32. The method according to claim 31 wherein the semiconductor switch is an insulated-gate bipolar transistor.

Description

DESCRIPTION OF THE DRAWINGS

[0050] FIG. 1 is a schematic representation of a typical elevator installation;

[0051] FIG. 2 is a schematic of the main components of the electromechanical brake from FIG. 1,

[0052] FIG. 3 is a schematic representation of a control device for controlling the brake from FIGS. 1 and 2, comprising a brake opening device known from the prior art;

[0053] FIG. 4 is a schematic representation of output pulses of the brake opening device from FIG. 3;

[0054] FIG. 5 is a schematic representation of jerky movements in the elevator car during the opening process of the brake opening device, as shown in FIG. 4;

[0055] FIG. 6 schematically shows a brake opening device according to the invention in accordance with an embodiment of the invention;

[0056] FIG. 7 shows a flowchart of a method according to the invention for moving an elevator car of an elevator in order to evacuate passengers from the elevator car in the event of a power failure; and

[0057] FIG. 8 shows a speed profile of an evacuation process which is carried out by the method according to the invention.

DETAILED DESCRIPTION

[0058] FIG. 1 shows an elevator installation with which the method according to the invention and the device according to the invention can be used. The elevator 1 moves in a shaft and comprises a counterweight 2 and an elevator car 4 which move in opposite directions along guide rails. Suitable suspension means 6, such as belts or ropes, connect the counterweight 2 and the elevator car 4. The suspension means 6 are connected to the counterweight 2 at one end, run over a traction sheave 8 which is located in the upper region of the shaft, and are connected to the elevator car 4 at the other end.

[0059] The drive sheave 8 is driven by the motor 12 via a shaft and is braked by the brakes 14, 16. The use of at least two brakes is required (e.g., by EN81-1:1998). Accordingly, the embodiment has two independent electromechanical brakes 14 and 16 which act on the shaft of the motor 12 via a brake disk. As an alternative to the brake disks, the brakes could act on a brake drum, as described in WO 2007/094777 A2.

[0060] Electrical energy comes from the main energy supply and is fed through the main contacts of the circuit breaker JH in three phases L1, L2 and L3 via the frequency converter FC to the motor 12. The frequency converter FC has a rectifier 20 which converts the AC voltage from the main energy supply into a DC voltage in the DC link 22. The DC voltage in the DC link 22 acts as an input for the converter 24, which converts the DC voltage into an AC voltage for powering the motor 12. The inverter 24 comprises a large number of power semiconductors, such as IGBTs, which are controlled by a PWM signal from the motor controller MC.

[0061] The mode of operation of the elevator 1 is controlled by an elevator controller EC. The elevator controller EC receives calls from the passengers, which they enter via the call panels on the respective floors. Before a call is processed by the elevator installation, a brake control device 40, which in this embodiment is designed as part of the frequency converter FC, will generate a current signal I to release the brakes 14, 16. The movement of the motor 12 is monitored by an encoder 26 in this embodiment. The encoder 26 is mounted on the traction sheave 8 or directly on the motor shaft and functions as a speed determination device. A speed signal V from the encoder 26 is fed back to the controller MC in the frequency converter FC. The unit MC can thus determine parameters such as the position, speed and acceleration of the elevator car 4. In addition or as an alternative, a magnetic tape 70 can be installed in the shaft and a magnetic reading device 68 can be installed on the elevator car 4 to function as a speed determination device 66. The magnetic reader 68 on the elevator car 4 runs along the magnetic tape 70 during a vertical movement. Due to the design of the magnetic tape having different magnetic zones, the magnetic reading device can determine the movement of the elevator car 4 in the shaft and parameters such as the speed, and acceleration can be derived.

[0062] Although the brake controller 40 is shown in FIG. 1 as part of the frequency converter FC, it is clear to a person skilled in the art that the brake controller 40 can also be formed in a separate housing outside the frequency converter FC or as part of the elevator controller EC.

[0063] FIG. 2 is a schematic representation of the main components of the electromechanical brakes 14 and 16 from FIG. 1. Each of the brakes 14, 16 is connected by a cable to a brake controller 40 and comprises an actuator 30 and an armature 36 on which a brake pad 38 is mounted.

[0064] The actuator 30 includes one or more springs 32 arranged to push the armature 36 in a brake closing direction C when braking. The armature 36 is thus biased in a direction C toward the brake disk 18. In addition, the brake comprises a brake coil 34 mounted in the actuator 30. The coil 34 exerts an electromagnetic force on the armature 36 in the brake opening direction O against the spring force of the springs 32 when the coil is energized and thus moves the armature 36 away from the brake disk 18 and thus opens the brake.

[0065] FIG. 3 is a schematic representation of a brake control device 40 of FIGS. 1 and 2 in combination with a pulse generator (PEBO) known from the prior art. In normal operation of the elevator 1, when sufficient energy is available in the main energy supply, a DC voltage from the main energy supply is selectively fed to the coil 34 through the brake contact or brake relay BR, as shown schematically. In normal operation, the brakes 14, 16 are open when the brake relay BR is closed and thus a current I flows from the positive output +V through the coil 34 to the brakes 14, 16 and toward the ground connection 0V. When the brake relay BR is open, the brake coils 34 are simultaneously disconnected from the energy supply and the springs 32 move the armature 36 in direction C such that the brake pads 38 come into contact with the brake disk 18 and the brakes block movement of the elevator system.

[0066] For ease of use, the device PEBO comprises an independent energy supply, in this case a battery 52, which provides the electrical power for the pulse generator 56. A converter 54 can optionally be present which adapts the voltage level of the battery 52 to the required voltage level of the generator 56. The pulse generator 56 can thus supply appropriate pulses to the coils 34 of the brakes 14, 16.

[0067] In order to carry out manual evacuation of the elevator car 4 in the event of a power failure, the relevant personnel must first turn off the main energy supply switch JH (see FIG. 1) upon arrival at the control facility to ensure that the evacuation procedure is not interrupted even if the main energy supply is operational again. The manual evacuation switch JEM of the device PEBO can then be switched on and thus an electrical connection can be established between the generator 56 and the brake coils 34. Another manual evacuation switch DEM is then actuated so that the pulse generator 56 and the battery 52 are connected to one another. The generator 56 will then deliver a series of electrical pulses to the brake coils 34, as shown in FIG. 4. For each of the braking pulses, the brake opens and the elevator car 4 can move, under the influence of gravitational force and in the presence of an imbalance between the mass of the elevator car 4 and the counterweight 2, in a manner corresponding to the imbalance. The manual evacuation switch DEM can be repeatedly pressed until the elevator car 4 arrives at a floor. In this method according to the prior art, it takes a plurality of pulses to move the car and thus a plurality of actuations of the switch DEM. The duration of a pulse, i.e., from time t.sub.0 to time t.sub.1, is always the same length and is 72 ms, for example. The jerky movements triggered by these pulses can be measured by a sensor in the elevator car 4 and are shown schematically in FIG. 5.

[0068] FIG. 6 shows a brake opening device 60 according to the invention instead of the device PEBO. The components already shown in FIG. 3 and previously described are identified by the same reference numbers and will not be described again, reference being made to the previous description. In contrast to the pulse generator 56 in the device PEBO, the brake opening device 60 according to the invention comprises a control device 64 having two switches 62, which in this embodiment are in the form of semiconductor switches, specifically in the form of IGBTs. The semiconductor switches are arranged in the electrical path from the battery 52 to the brakes 14 and 16 at the positive pole of the battery, which is routed to the coils 34 via two lines. In addition to the switches DEM and JEM, the switches 62 thus make it possible for the energy supply from the battery to the brakes 14, 16 to be interrupted. If the two switches DEM and JEM are closed, the energy flow from the battery 52 to the brakes 14 and 16 can be modulated via the switch 62. For this purpose, the semiconductor switches can be switched on and off at a high frequency, it being possible for the power actually transmitted from the battery to the brakes 14, 16, in particular to the coils 34 of the brakes, to be set via the on and off duration. Due to the presence of a switch 62 for each of the brakes 14 and 16, each of the brakes can be activated individually. The activation makes it possible to regulate the brake in such a way that it brakes the elevator system so that, at a given imbalance between the elevator car and the counterweight, a substantially constant speed is set in the elevator system. The brake opening device according to the invention thus enables an evacuation process in which the elevator car is moved at a substantially constant speed. The jerky movements from FIG. 5 can be at least partially eliminated. The movement takes place continuously. The movement includes an acceleration phase in which the speed is accelerated from zero to the specified target speed, then a movement phase in which the elevator car moves at a constant speed, and finally a braking phase in which the elevator car is decelerated below the target speed to a standstill. These speed profiles are shown in FIG. 8.

[0069] FIG. 7 shows a flow chart of a method according to the invention for evacuating passengers from an elevator car who are stuck in the elevator car in the event of a power failure. Typically, such a method is carried out by a device from FIG. 6.

[0070] If the main energy supply fails in step S1, the brake contact or the brake relay BR is opened automatically and the brakes 14, 16 close immediately and thus prevent the elevator car 4 from continuing to move. If passengers are stuck in the elevator car 4, they can order the evacuation by actuating an emergency call switch.

[0071] Upon arrival, the service engineer will gain access to the control unit and turn off the main circuit breaker JH therein in step S2 to ensure that the evacuation method will not be interrupted even if the main energy supply is restored.

[0072] In step S3, the method is prepared by the brake opening device 60. It is ensured that the speed information can be read by the speed determination device. Also in step S3, the manual evacuation switch DEM is pressed by the service technician in order to connect the brake opening device 60 to the battery 52.

[0073] In step S4, the brake opening device 60 will then activate the brake coils 34 using a specific electrical power so that the elevator car 4 moves under the influence of gravitational force and depending on the imbalance between the mass of the car 4 and the counterweight 2. The brake is thus moved from a closed position to an at least partially open position in this step.

[0074] In order for the movement to take place at a constant speed, an actual speed of the elevator car is determined in step S5. This can be done by the encoder 26 and/or the magnetic tape 70 and the magnetic reader 68.

[0075] In a step S6, the measured actual speed is compared with a specified target speed. This takes place in the brake opening device 60. In other embodiments, this can also take place in another control device, for example in the elevator control device EC or in the motor control device MC.

[0076] In the next step S7, the electrical power transmitted to the brake is adjusted, i.e., reduced or increased, according to a deviation of the actual speed from a specified target speed, so that the actual speed substantially corresponds to the target speed.

[0077] If it is determined in step S8 that the car has reached a floor, the method proceeds to step S9. If no floor has yet been detected, the method jumps back to step S5 and runs through steps S5 to S7 again until it is then determined at a point in time that the floor has been reached.

[0078] If it is determined that the floor has been reached, the service technician can go to the corresponding floor in step S9 and open the doors of the elevator car there manually in order to evacuate the passengers.

[0079] In step S10, the elevator can subsequently be prepared again for normal operation. In step S11, the evacuation method is then completed.

[0080] In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.