Otis Elevator Company

Harry Z Huang

Chouhwan Moon

Juan A Lence Barreiro

Robert H Mashiak

Gary L Freeland

Jun Liu

Ronald R Pepin

Juan A Lence-Barriero

Variable thresholds ( ) are generated in response to an average defect rate ( ) generated under certain conditions ( ), excesses of which can set an internal flag ( ). If an information request ( ) or service personnel visit to the elevator site ( ) occur, the internal flag, or the upward adjustment of the average defect rate ( ) can generate a maintenance flag ( ) which ultimately results in a maintenance recommendation message related to the particular parameter having a notable defect.

Condition-based, auto-thresholded elevator maintenance

The mean number of elevator door reversals, &mgr;, in groups of related door reversals, and the standard deviation, &sgr;, from the mean, are used to determine the likelihood that door reversals are caused by passenger interference; the likelihood is low if a recent number of reversals exceeds &mgr;&plus;3&sgr;, , is medium if two out of three recent reversals exceed &mgr;&plus;2&sgr;, and otherwise is high. The floors at which related notable elevator features occur are compared to determine a floor factor, F, depending on whether the notable feature occurs only at one floor or at more than one floor. Estimated probabilities, P&prime;(S/C), that any component, C, will result in a symptom, S, (where S&equals;first and second notable features in a related group and the accompanying floor factor, F) are provided by experts; the probability of P&prime;(C) of any failure being of any given component is determined from failure history; and an estimated probability, P&prime;(C/S), that symptom S is caused by component C is given by:

Service information derived from elevator operational parameters

Elevator events and conditions are monitored so as to determine features which are notable with respect to service including repair and maintenance, a name label is stored chronologically in a log upon each occurrence of a notable feature. Attributes of the feature stored chronologically with the feature, may include the date and time, the duration of the feature or a preceding condition, the point of time in a run when the notable feature occurred, the direction of elevator car travel and the floor location of the elevator related to the notable feature. Separation markers are generated to separate notable features which relate to each other from those that do not, each marker having floor number, time and date stamps and the duration between the first feature related thereto and the last feature related thereto stored chronologically therewith. Features include door reversals, loss of non-door safeties, failure making door lock switches, door rebound, doors open too long, and doors open in flight.

Elevator behavior reported in occurrence-related groups

Braking distance (S,) and traction slippage distance (S,) are measured with an empty elevator car (,) traveling upwardly (S,, S,) and downwardly (S,, S,). From these measured distances, the following are calculated and/or determined: maximum and minimum deceleration, a,, a,, braking force, F,, available to stop the car when traveling downwardly with a full load; braking force available when traveling upwardly, F,, and downwardly, F,, while empty; difference in braking force provided by two sides of the brake; whether the relationship of traction slippage to tension ratio ((FIG. 5) is within the safe, linear portion or within the unsafe, non-linear portion; and whether leveling errors are caused by faulty brakes, excess traction slippage, or neither.

Growing community of inventors

Plainville, CT, United States of America

Harry Z Huang