Jerk limiting in elevator rescue system

Patent metadata

Field	Value
Publication number	US-10273116-B2
Application number	US-201615052685-A
Country	US
Kind code	B2
Filing date	Feb 24, 2016
Priority date	Mar 23, 2015
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

An elevator rescue system allows an elevator car of an elevator to be moved in an emergency situation. The elevator includes an elevator motor acting on hoisting ropes by which the elevator car is suspended including at least one electro-mechanical brake and an encoder outputting a signal corresponding to its speed. The rescue system includes a back-up power source, a jerk monitoring circuit connected to the encoder and including a memory storing an upper threshold value for the derivative of car acceleration, a brake feed circuit controlled by the jerk monitoring circuit, and a release switch connected to the jerk monitoring circuit and/or to the brake feed circuit. The release switch activates the brake feed circuit to release the brake, and initiate the jerk monitoring circuit to compare the derivative of car acceleration derived from the encoder signal with the stored first upper threshold value, and forwards a control signal to the brake feed circuit to initiate/stop braking depending on the comparison result.

First claim

The invention claimed is:

1. A rescue system for moving an elevator car of an elevator in an emergency situation, which elevator includes an elevator motor acting on hoisting ropes by which the elevator car is suspended and/or moved, which elevator motor comprises at least one electro-mechanical brake and an encoder outputting a signal corresponding to its speed, which system comprises:
a back-up power source,
a jerk monitoring circuit connected to the encoder and comprising a memory for at least one first upper threshold value for the time derivative of the car acceleration,
a brake feed circuit which is controlled by the jerk monitoring circuit,
at least one release switch which is connected to the jerk monitoring circuit and/or to the brake feed circuit,
wherein the operation of the release switch activates the brake feed circuit to release the brake, and initiates the jerk monitoring circuit
the jerk monitoring circuit comparing the derivative of the car acceleration derived from the encoder signal with the stored first upper threshold value so that when the derivative of acceleration exceeds the threshold the jerk monitoring circuit supplies, a control signal to the brake feed circuit to initiate/stop braking depending on the comparison result.

2. The system according to claim 1 , comprising at least one car location indicator connected to the jerk monitoring circuit or to the brake feed circuit, wherein the control signal produced by the jerk monitoring circuit is supplied to the brake to stop the elevator car when the jerk monitoring circuit or the brake feed circuit receives a signal from the car location indicator, that the car has reached a floor area.

3. The system according to claim 1 or 2 , wherein the brake comprises
a spring biasing the brake into a gripping state and
an electro-magnetic brake release to push the brake into a release state against the force of the spring.

4. The system according to claim 1 , wherein the brake feed circuit includes a DC/DC voltage converter, which is connected to the backup power source.

5. The system according to claim 1 , wherein the backup-power source is a battery or an accumulator.

6. The system according to claim 1 , wherein the brake feed circuit comprises a semiconductor switch, which is connected to an output of the brake feed circuit, whereby the semiconductor switch is coupled to the jerk monitoring circuit.

7. The system according to claim 1 , wherein the operation of the release switch activates the jerk monitoring circuit to forward the control signal to the brake feed circuit to release the brake.

8. The system according to claim 1 , wherein the control signal is a binary signal which is “high” to release the brake and which is “low” to activate the brake.

9. The system according to claim 1 , wherein the power for the operation of the brake feed circuit and/or of the jerk monitoring circuit is obtained from the back-up power source.

10. The system according to claim 1 , wherein the car speed of the elevator is monitored by an overspeed governor.

11. The system according to claim 1 , comprising a dynamic braking circuit short-circuiting the windings of the elevator motor, which dynamic braking circuit is powered by the back-up power source.

12. The system according to claim 11 , wherein the dynamic braking circuit uses an inverter of the elevator motor drive including solid state switches for dynamic braking, whereby a dynamic braking control gets its operating supply voltage from a DC intermediate circuit of the inverter.

13. The elevator including the system according to claim 1 .

14. A method of moving an elevator car of an elevator in an emergency situation, which elevator includes an elevator motor acting on hoisting ropes by which the elevator car is suspended and/or moved, which elevator motor comprises at least one electro-mechanical brake and an encoder outputting a signal corresponding to its speed, using
a back-up power source,
a brake feed circuit to operate the electro-mechanical brake,
at least one release switch to initiate a rescue operation, the method comprising:
releasing the brake in response to actuation of the release switch to move the elevator car in the direction of a floor, and
monitoring acceleration of the elevator car and activating the brake when the derivative of acceleration exceeds an upper threshold value.

15. The method according to claim 14 , further comprising using at least one car location indicator to monitor the level of the elevator car with respect to the floor level to which the elevator car approaches,
said method allowing the car is to be moved until the car location indicator indicates arrival of the elevator car in a floor area, where current output to the brake is stopped to halt movement of the elevator car.

16. The method according to claim 14 or 15 , wherein after activation of the brake after exceeding the upper threshold value the brake is opened again after the car speed has dropped to a lower threshold value.

17. The method according to claim 14 wherein the operation of the release switch starts the jerk monitoring unit to control dynamic braking of the elevator motor via a dynamic braking circuit.

18. The method according to claim 14 whereby an overspeed governor is used to monitor the elevator car speed.

19. The method according to claim 14 wherein the method is performed by a system
a jerk monitoring circuit connected to the encoder and comprising a memory for at least one first upper threshold value for the car acceleration and/or its time derivative; and
a brake feed circuit which is controlled by the jerk monitoring circuit;
wherein the release switch is controlled by the jerk monitoring circuit;

wherein the releasing the brake activates the brake feed circuit to release the brake, and initiates the jerk monitoring circuit by comparing the derivative of car acceleration as derived from the encoder signal with the stored first upper threshold value, and forwarding a control signal to the brake feed circuit to initiate/stop braking depending on the comparison result.

Assignees

• Kone Corp

Inventors

• Kattainen Ari
• Nakari Arto

Classifications

• B66B5/027 Primary

  to permit passengers to leave an elevator car in case of failure, e.g. moving the car to a reference floor or unlocking the door · CPC title

• B66B1/32 Primary

  effective on braking devices {, e.g. acting on electrically controlled brakes (brake control H02P, lift brakes per se B66B5/02)} · CPC title

• B66B5/044

  Mechanical overspeed governors · CPC title

• B66B3/02

  Position or depth indicators · CPC title

• B66B5/02

  responsive to abnormal operating conditions · CPC title