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EP-4735368-A1 - A SAFETY METHOD AND AN ELEVATOR DRIVE SYSTEM FOR AN ELEVATOR SYSTEM COMPRISING REDUCED BUFFERS

EP4735368A1EP 4735368 A1EP4735368 A1EP 4735368A1EP-4735368-A1

Abstract

The invention relates to a safety method for an elevator system (100) comprising reduced buffers (118a, 118b). The method comprises: detecting (210) a reduced braking force of a hoisting machinery brake arrangement, and adjusting (220) at least one limiting parameter limiting an elevator motion in response to detecting the reduced braking force, wherein the elevator motion represents a motion of an elevator car (102) of elevator system (100). The invention relates also to an elevator drive system (122) and an elevator system (100).

Inventors

  • KATTAINEN, ARI
  • Aitamurto, Juha-Matti

Assignees

  • KONE Corporation

Dates

Publication Date
20260506
Application Date
20230630

Claims (19)

  1. 1. A safety method for an elevator system (100) comprising reduced buffers (118a, 118b), the method comprises: detecting (210) a reduced braking force of a hoisting machinery brake arrangement, and adjusting (220) at least one limiting parameter limiting an elevator motion in response to detecting the reduced braking force, wherein the elevator motion represents a motion of an elevator car (102) of elevator system (100).
  2. 2. The method according to claim 1 , wherein the reduced braking force is detected during a condition monitoring test of the hoisting machinery brake arrangement.
  3. 3. The method according to any of the preceding claims, wherein the detecting the reduced braking force comprises detecting that a braking force of at least one hoisting machinery brake (114a, 114b) of the hoisting machinery brake arrangement decreases below a predefined braking force limit.
  4. 4. The method according to any of the preceding claims, wherein the adjusting (220) of the at least one limiting parameter comprises reducing (310) an overspeed limit of the elevator car (102).
  5. 5. The method according to claim 4, wherein the overspeed limit of the elevator car (102) is reduced to a rated striking speed of the buffers (118a, 118b) or to a speed value corresponding to the reduced braking force.
  6. 6. The method according to any of the preceding claims, wherein the adjusting (220) of the at least one limiting parameter comprises reducing (320) limit values of Emergency Terminal Speed Limiting (ETSL) devices of the elevator system (100).
  7. 7. The method according to claim 6, wherein the limit values of the ETSL devices are reduced to a rated striking speed of the buffers (118a, 118b) or to limit values corresponding to the reduced braking force.
  8. 8. The method according to any of the preceding claims, wherein the adjusting (220) of the at least one limiting parameter comprises reducing (330) a maximum speed of an elevator speed profile.
  9. 9. The method according to claim 8, wherein the maximum speed of the elevator speed profile is reduced to a rated striking speed of the buffers (118a, 118b) or to a maximum speed value corresponding to the reduced braking force.
  10. 10. An elevator drive system (122) of an elevator system (100) comprising reduced buffers (118a, 118b), the elevator drive system (122) comprising: at least one processor (410); and at least one memory (420) including computer program code (425); wherein the at least one memory (420) and the computer program code (425) are configured to, with the at least one processor (410), cause the elevator drive system (122) to perform: detect a reduced braking force of a hoisting machinery brake arrangement, and adjust at least one limiting parameter limiting an elevator motion in response to detecting the reduced braking force, wherein the elevator motion represents a motion of an elevator car (102) of elevator system (100).
  11. 11. The elevator drive system (122) according to claim 10, wherein the reduced braking force is detected during a condition monitoring test of the hoisting machinery brake arrangement.
  12. 12. The elevator drive system (122) according to any of claims 10 or 11 , wherein the detection of the reduced braking force comprises that the elevator drive system (122) is configured to detect that a braking force of at least one hoisting machinery brake (114a, 114b) of the hoisting machinery brake arrangement decreases below a predefined braking force limit.
  13. 13. The elevator drive system (122) according to any of claims 10 to 12, wherein the adjusting of the at least one limiting parameter comprises that the elevator drive system (122) is configured to reduce an overspeed limit of the elevator car (102).
  14. 14. The elevator drive system (122) according to claim 13, wherein the overspeed limit of the elevator car (102) is reduced to a rated striking speed of the buffers (118a, 118b) or to a speed value corresponding to the reduced braking force.
  15. 15. The elevator drive system (122) according to any of claims 10 to 14, wherein the adjusting of the at least one limiting parameter comprises that the elevator drive system (122) is configured to reduce limit values of Emergency Terminal Speed Limiting (ETSL) devices of the elevator system (100).
  16. 16. The elevator drive system (122) according to claim 15, wherein the limit values of the ETSL devices are reduced to a rated striking speed of the buffers (118a, 118b) or to limit values corresponding to the reduced braking force.
  17. 17. The elevator drive system (122) according to any of claims 10 to 16, wherein the adjusting of the at least one limiting parameter comprises that the elevator drive system (122) is configured to reduce a maximum speed of an elevator speed profile.
  18. 18. The elevator drive system (122) according to claim 17, wherein the maximum speed of the elevator speed profile is reduced to a rated striking speed of the buffers (118a, 118b) or to a maximum speed value corresponding to the reduced braking force.
  19. 19. An elevator system (100) comprising: an elevator car (102) arranged to travel along an elevator shaft (104); a reduced buffer arrangement comprising reduced buffers (118a, 118b); a hoisting machinery brake arrangement comprising at least two hoisting machinery brakes (114a, 114b); and an elevator drive system (122) according to any of claims 10 to 18.

Description

A SAFETY METHOD AND AN ELEVATOR DRIVE SYSTEM FOR AN ELEVATOR SYSTEM COMPRISING REDUCED BUFFERS TECHNICAL FIELD The invention concerns in general the technical field of elevator systems. Especially the invention concerns safety of elevator systems. BACKGROUND An elevator system comprises an elevator car configured to travel along an elevator shaft between floors, an elevator control system, and hoisting machinery system. The elevator car is driven with the hoisting machinery system by means of hoisting ropes, which run via a traction sheave of the hoisting machinery system. The elevator control system comprises a drive system for controlling an electric motor of the hoisting machinery system (e.g. power feed to the electric motor, speed of the electric motor, and torque of the electric motor) in order to move the elevator car along the elevator shaft. The drive system generates for example at least one drive profile, e.g. a speed profile and/or a torque profile, and drives the elevator car in accordance with the generated at least one drive profile. The elevator system comprises further a safety equipment, such as a buffer, arranged in a pit of the elevator shaft to soften stopping of a motion the elevator car, if the elevator car attempts to run over a bottom floor towards the pit, by absorbing kinetic energy of the elevator car. Further, a separate buffer may be provided in the pit to soften stopping of a motion of a counterweight, if the elevator car attempts to run over a top floor towards a top of the elevator shaft, by absorbing kinetic energy of the counterweight. Typically, the buffers are dimensioned according to a nominal speed of the elevator car. In other words, typically a rated striking speed of the buffers corresponds to the nominal speed of the elevator car. In some cases, instead of the typical buffers, the elevator system may comprise reduced buffers, wherein the height of the buffers is reduced. The reduced buffers may be dimensioned so that the rated striking speed of the buffers is lower than the nominal speed of the elevator car. The elevator system comprises further hoisting machinery brakes, which may be applied to stop unintended motion of the motion of the elevator car. Further, the elevator system may comprise an overspeed governor, which actuates electrically the hoisting machinery brakes to stop the motion of the elevator car if the speed of the elevator car exceeds an overspeed limit. Different safety functions of the elevator system may require different braking forces of the hoisting machinery brakes to stop the motion of the elevator car. For example, in response to detecting that the speed of the elevator car exceeds the overspeed limit, in case of the conventional buffers, i.e. not reduced buffers, a braking force, which enables that the motion of the elevator car can be slowed down, is sufficient, because it does not matter, if the elevator car runs into, i.e. collides, to the buffers, because the rated striking speed of the buffers corresponds to the nominal speed of the elevator car. However, in case of the reduced buffers a higher braking force is required, because the rated striking speed of the buffers is lower than the nominal speed of the elevator car. Typically, the drive system of the elevator system may be used for monitoring the braking force of the hoisting machinery brakes. Conventionally, in response to detecting by the drive system that the braking force of the hoisting machinery brakes is reduced, the elevator system needs to be taken out of service. SUMMARY The following presents a simplified summary in order to provide basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention. An objective of the invention is to present a method, and an elevator drive system for an elevator system comprising reduced buffers and an elevator system. Another objective of the invention is that the method and the elevator drive system for an elevator system comprising reduced buffers and the elevator system enables that the operation of the elevator system may be continued when a reduced braking force of a hoisting machinery brake arrangement is detected. The objectives of the invention are reached by a method, an elevator drive system and an elevator system as defined by the respective independent claims. According to a first aspect, a safety method for an elevator system comprising reduced buffers is provided, wherein the method comprises: detecting a reduced braking force of a hoisting machinery brake arrangement, and adjusting at least one limiting parameter limiting an elevator motion in response to det