Elevator – industrial lift truck – or stationary lift for vehicle – With monitoring – signalling – and indicating means – Monitors operational parameter
Reexamination Certificate
2000-07-19
2001-12-04
Salata, Jonathan (Department: 2837)
Elevator, industrial lift truck, or stationary lift for vehicle
With monitoring, signalling, and indicating means
Monitors operational parameter
Reexamination Certificate
active
06325179
ABSTRACT:
TECHNICAL FIELD
This invention relates to determining the condition of an elevator brake system, the traction sheaves and ropes, the ability of the elevator to decelerate properly, whether the elevator will stop with full load, and cause of leveling errors.
BACKGROUND ART
It has been common to have elevator mechanics check brake operation visually by determining when the actual braking operation begins by visual measuring of distance. Such a test is subject to human error: for example, an error of only 100 microseconds in determining the actual beginning of the braking operation will result in an error of one quarter of a meter if the elevator speed were 2.5 meters per second. In certain modern elevators operating at 10 meters per second, the error would be a full meter. Such tests also require that the elevator be taken out of service for some period of time. The test can only be performed with a mechanic at the elevator site, and will require between five minutes and twenty minutes of the mechanic's time to carry out the test. Such tests are only qualitative, resulting in pass/fail or poor/fair/good indications of results.
More recently, external devices have been utilized to measure the parameters of the elevator brake system. Such devices are usually quite complex, require additional hardware attached to the elevator, are difficult to operate, and require great expertise in order to interpret the result.
Any of the tests overtly performed with human intervention must be performed according to a schedule, such as at regular intervals of time, or a schedule based upon elevator usage.
DISCLOSURE OF INVENTION
Objects of the invention include determining the condition of an elevator brake system and the traction rope and sheaves, and parameters related thereto: without the need for human intervention; quantitatively, resulting in discrete values which can determine compliance with regulatory code; eliminating errors, including human errors; which can be performed in very short periods of time; which do not require that additional devices be added to the elevator system to make measurements; which provides easily interpreted results; which can be performed and utilized without requiring great expertise; and which, because of its nature, can be performed with substantially any desired frequency, at low maintenance costs and with adequate safety.
Other objects of the invention include provision of simple, automated, quantitative reliable elevator monitoring: that does not require human intervention or the addition of new measuring or sensing devices; which can provide sufficient information to compute the car deceleration for comparison with regulatory codes; to determine if the mechanical brake will stop the elevator with 125% of rated load as required by regulatory codes; to determine the condition of the brake system; to determine the condition of the traction sheave and ropes; and to discern the cause of leveling errors.
According to the present invention, the slipping distance (that is, the difference in the position of the elevator rope drive from the position of the elevator itself as a consequence of traction slippage between the rope and the sheave) as well as the braking distance, (that is, the distance the elevator travels after a command to stop the elevator mechanically by means of the brake) are utilized in energy balance equations and velocity/acceleration/distance equations to determine maximum and minimum car decelerations for comparison with regulatory code requirements, to determine whether the car will be able to stop with 125% rated load, to detect the general condition of the brake system, to determine specific adjustments required to the brake system, to detect the general condition of the traction sheave and ropes, and to determine the cause of leveling errors.
According to the invention, the elevator car, when determined to be empty, is caused to maneuver automatically, including commanded emergency mechanical stops during rated speed runs while noting the settings of a motor position encoder and of a car position encoder, but, if a car position encoder is not available in the system, an additional nominal speed run is made between known distances in the hoistway.
Other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of exemplary embodiments thereof, as illustrated in the accompanying drawing.
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Barreiro Juan A. Lence
Huang Harry Z.
Moon Chouhwan
Otis Elevator Company
Salata Jonathan
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