Elevator Ropes Research Articles

Mechanical properties of elevator ropes and belts exposed to corrosion and elevated temperatures

Abstract Safety in elevators is extremely important phenomenon. Elevator accidents occurring today are at a level that seriously threatens the safety of life and property, and especially elevator ropes and belts have a very important place in these systems in order not to endanger human life. As with every mechanism, stress, fatigue and deformations occur in elevator parts and equipments such as ropes and belts over time causing impairment and reduce their strength. In this study, artificial defects were given to the 8 × 19 Warrington steel wire rope and polyurethane coated elevator belt to examine the effects of different type of corrosion and elevated temperature deterioration on mechanical properties and their comparisons were made. Results indicate that the percent reduction in lifting capacity of the elevator belt investigated was lower than that of the 8 × 19 Warrington rope in all degradation types examined.

스프링 양단 지지 케이블의 고유진동 해석을 위한 허용함수와 준 비교함수의 선택에 대한 고찰

Natural vibration analysis of cables is required in various fields, such as transmission lines and elevator ropes. Actual cables are often non-uniform. Because an exact solution is difficult to calculate in this case, an approximate solution must be calculated through numerical analysis. It is important to define the admissible function in the assumed method, which is widely used among numerical analysis methods. However, selecting an admissible function for a problem in which only geometric boundary conditions exist, such as spring-end support cable, is difficult. In this study, we propose the admissible and quasi-comparison functions for the addressed problem and compare the results to the finite element method results. This study can be used for the analysis of various structures in which cables are used.

Smart elevator systems

Effective vertical mobility is a crucial element in the design and construction of tall buildings. This paper reviews recent “smart” developments in elevator technologies and analyzes how they affect the construction and operation of tall buildings. In an approachable and non-technical discourse, it maps out, arranges, and compiles complicated and dispersed information on various elements of elevator design. It discusses hardware-based machinery, such as AC and gearless motors, machine-room-less (MRL) elevators, regenerative drives, elevator ropes, and LED lighting, as well as software-based solutions, such as destination dispatching systems, people flow solutions, standby mode, and predictive maintenance applications. Future vertical transportation models are also discussed, including multi-directional elevators, and circulating multi-car elevators. Lastly, the paper suggests fruitful avenues for further studies on the subject, such as robotics, 3D printing, and the impact of COVID-19 pandemic on elevator design.

Substantiation of Passenger Elevators Maintenance Intervals Based on Studies of Modes and Conditions of Their Operation

Introduction. Maintenance is one of the factors of elevator systems safe operation. In regulatory documents, the influence of the loading mode of elevators on the frequency of maintenance is not taken into account and is assumed to be the same for objects operating in disparate conditions. This suggests the need to determine rational intervals between maintenance to ensure safe and economically feasible operation of the equipment in question. The work objective is to substantiate the required maintenance frequency of passenger elevators based on comprehensive assessments of their technical condition.Materials and Methods. The domestic and foreign experience of choosing the maintenance frequency of elevator units is considered. The paper evaluates the possibilities of substantiating the required maintenance intervals on the basis of established comprehensive assessments of technical condition, taking into account the conditions and operating modes. Since the problem has no direct analytical solution, an alternative approach is proposed. It is based on the hypothesis of the interrelation between the regulatory resource characteristics of assemblies and the modes and conditions of their operation. The authors obtained the necessary indicators through measurements in high-rise apartment buildings in Rostov-on-Don, experiments and adequate simulation modelling.Results. A structural and logical model has been developed to solve this problem. It consists of procedures that can be described in detail and clarified. A method for adjusting the maintenance frequency of elevators is proposed and tested. The standards of the system resource in terms of time and number of work cycles for the control time are summarized and tabulated. In this light, the gearbox, electric motor, brake, door drive and elevator ropes in 9-storey buildings are described at a cabin speed of ≤ 1 m/s. For example, the paper provides the calculated normative indicators:Kmcp норм — coefficient of net machine time (NMT);ncp норм — specific number of switching-on of the main drive and the doorAccording to the calculation results, Kmcp норм for the electric motor is 0.228; ncp норм for the brake is 1.065 per NMT minute. To assess the overall load level, the resulting technical condition of the elevator and its main components, a single generalized indicator is proposed — the load index WΣ. It is calculated as the sum of coefficients reflecting the relative level of load on the elevator assembly. It is established that as the resource is being depleted, while maintaining the value of time and power indicators, the estimated maintenance frequency will decrease. The recommended change threshold is 15–20 %.Discussion and Conclusion. The developed methodology for assessing the technical condition of the elevator unit allows us to develop a complex index by which we can judge the need to revise the regulatory intervals of the elevator unit assemblies. The proposed procedures are applicable to existing, installed and designed elevators. Simulation modeling in a specially developed computer program determines the main indicators of the technical condition of the power units of the elevator: the coefficient of net machine time, switching-on specific number, the power load and the share of the expired service life. Simulation modelling also takes into account the parameters of the building: population density and random external and internal influences. The method of adjusting the maintenance frequency allows you to quickly plan and optimize the costs of operating elevator equipment without losing the level of reliability and safety.

Method of estimating the lateral vibration of an elevator rope from the vertical vibration of a compensating sheave

ABSTRACT Observing the vibration of the elevator ropes in an elevator shaft is a difficult task. Although several methods of observing the displacement using image processing or laser displacement meters and then estimating the vibration through an observer or a Kalman filter have been developed, it is difficult to install sensors because of the movement of the elevator car and the thinness of the rope as an observation target. Therefore, in this study, we focus on a pulley called a compensating sheave that does not change its lateral position as the car and ropes move. The horizontal vibration of the ropes causes the compensating sheave to vibrate in the vertical direction. A method of estimating the horizontal vibration from this vertical vibration using arc length calculations and a short-time fast Fourier transform is proposed. First, the vertical vibration of the compensating sheave is distributed to the various mode responses based on the predominant frequency of the vertical vibration. The mode-decomposed vertical vibration is then converted into a horizontal mode response using an arc length relational expression. Analysis of seismic response data confirms that the proposed method can estimate the 1st, 2nd, and 3rd horizontal mode responses from the vertical vibration.

Study on vibration characteristics of elevator ropes by elemental test

Elevators are essential for means of a vertical transportation. Recently, high-rise buildings are increasing. Those elevator ropes become longer. As a result, the natural period of the elevator rope becomes closer to the natural period of the high-rise building. The risk of resonance increases. When the high-rise buildings receive an external force such as the strong wind and the earthquake, the elevator rope may sway intensely. The rope may be hooked to the equipment in the hoistway. The accurate analysis of a rope is important to grasp the actual rope behavior during an earthquake. In this study, the free vibration test on elevator ropes is carried out with an element testing equipment. Furthermore the vibration characteristic of elevator ropes is investigated. In this paper, the free vibration test was carried out with the 5 mm-diameter elevator rope, further the vibration characteristic was investigated. As a result, it was confirmed that the damping ratio of the elevator rope depends on the displacement of the horizontal direction.

Rope tension analysis based on single spring model against elevator rope

Elevators run vertically by suspension ropes, therefore each rope has to be adjusted correctly to fulfill each tension balance. That contributes to establish a long life against elevator ropes. If a groove wear of the traction sheave causes difference against other grooves, the difference induces rope tension fluctuation while changing the car position. Conventional elevator models to evaluate the rope tension have not considered the detailed winding behavior of the rope on the sheave. As the winding amount of the rope contains the rope deformation, the deformation should be considered to evaluate the rope length and the rope tension in an elevator tension model. This paper shows a simple elevator model with a single spring model against the rope. The derived model can not only calculate the appropriate winding amount against the rope spring model, but also get a faster solution even though the elevator system has a complicated roping configuration. The proposed simulation model is validated by experiments.

Study on vibration characteristics of elevator ropes by elemental test

Study on vibration characteristics of elevator ropes by elemental test

An improved anti-rollback control algorithm for gearless traction motor in elevator applications

Permanent magnet synchronous motors are widely used in elevator applications. This is due to their high efficiency and reliability, whereby motors are directly connected to the elevator ropes without the need of having a gearbox. This efficient system comes with some new challenges regarding the control of the motor. Since no gearbox is added to the system, the motor speed oscillations are directly transferred to the elevator cabin. This urges the need of having a smooth control algorithm to suppress the measurement noises generated by the absolute encoder especially at low speed. On the other hand, whenever the mechanical brakes are released, the speed controller needs to react quickly to prevent the cabin from rolling back. In order to overcome these challenges, this paper presents an improved speed control algorithm that reacts quickly in transient state to reduce the rollback of the cabin and slowly at steady state to ensure smooth ride. The proposed controller is based on the combination of a Model Predictive Controller (MPC) along with a torque observer. It also benefits from being computationally less demanding unlike other MPC techniques. The proposed controller is experimentally tested on an elevator and then compared to classic controllers. Finally, conclusions are drawn.

Laboratory Device for Checking the Functionality of the Elevator Rope Sensors

Abstract The paper describes the structural design of a laboratory device that allows for presenting operation, simulating work procedures and checking functionality of the elevator “rope sensors” when equalizing different tensile forces in partial ropes of a rope system of traction elevators. The laboratory device is modified for checking operations of commonly used rope sensors. In an overwhelming number of cases, elevator technicians use them for setting up the unequally distributed tensile forces in elevator ropes. The device is equipped with three, mutually attached pulleys, over which the rope is installed. The unknown tensile force in the rope is determined by an “indirect method”, i.e. from the resultant of the forces of the rope bent over the pulleys, which have an effect on the force sensor. The tensile force along the rope axis can be determined numerically, but also experimentally, from the inclination angle of the rope installed on the pulleys, diameter of the pulleys, diameter of the rope and the force detected by the force sensor of the stretched rope. The paper presents experimentally obtained tensile force values at the rope sensor, deduced from stretching the rope. The paper also describes the procedure for determining the measured load in the rope by rope sensors of the SWR, SWK and RMT-1 types based on the variable axial force in the rope.

Structural design and mechanical performance evaluations of flexible and lightweight belt by CFRP

This research presents the structural design and mechanical performance evaluation results of a lightweight belt for high-rise elevators. Weight reduction of elevator components is indispensable in developing ultra-high-rise elevators. In this study, the structural design and performance evaluation of high-rise elevator ropes were carried out. The weight of the newly designed Carbon Fiber Reinforced Plastic (CFRP) belt was reduced by 30% compared with the original steel wire rope. The structural analysis results of the CFRP belt showed that the design criteria were met on the design load condition of the belt. Also, mechanical tests were executed to verify the mechanical characteristics of the newly developed belt, with the results showing that the belt had sufficient structural performance compared with conventional steel wire rope.

Theoretical and experimental investigation of effects of failures on the tensile endurance of elevator ropes

AbstractElevators have an important place in human life just after uprising demands in high rise buildings, skyscraper and luxury residence concepts have surged. Steel wire ropes provide permanent working safety and reliability in the elevator installations. Due to this reason steel wire ropes are one of the vital components of elevators. In this study, effects of discard criteria such as wire breaks, abrasive wear and corrosion where extents of those failures are defined by ISO 4344 standard on the tensile endurance of 6×19 Seale and 8×19 Warrington elevator ropes have been investigated theoretically and experimentally. Tensile endurances of rope samples that have different extents of failure have been determined by using tensile testing machine and comparison is made by undamaged samples for each rope separately. In addition, stress and strain values occurred on the elevator ropes investigated have also been presented. The most critical failure type has been found to be 24 wire breaks for 6×19 Seale rope with fiber core where lifting capacity reduced by 25.99 %. The most critical failure type has been found to be abrasive wear which is 0.1 mm in depth along 100 mm length for 8×19 Warrington rope with independent wire rope core where lifting capacity reduced by 7.93 %.

Analysis and control of vibration of ropes in a high-rise elevator under earthquake excitation

In this research, the vibration of elevator ropes, including the main rope and compensation rope are investigated simultaneously in a high-rise elevator system under earthquake excitation. Moreover, the paper presents a new control method to restrain the sway of both ropes. This study considers varying rope lengths during elevator operation which cause other system parameters such as natural frequency, and damping ratio to be time-variant variables. The dynamics of the ropes are analyzed by solving the governing non-stationary, nonlinear equation numerically. In order to mitigate the vibration of ropes in several motion conditions, particularly upwards movement, downward movement, stopped at the lowest position, and stopped at the highest position, an active equipment is installed at the compensation sheave. The stability of the system using the controller is analyzed at four states: without disturbance and static car, without disturbance and mobile car, including disturbance and static car, and including disturbance and mobile car. The efficiency of the controller used for dampening the vibration of elevator ropes is validated by numerical simulation results.

Optimal design of control device to reduce elevator ropes responses against earthquake excitation using Genetic Algorithms

Optimal design of control device to reduce elevator ropes responses against earthquake excitation using Genetic Algorithms

Vibration analysis of elevator rope with one vibration suppressor

The lateral vibration of elevator ropes for high-rise building, which is excited forcibly by the displacements of the building induced by wind forces, is numerically analyzed, and a new practical method for reducing the rope vibration by using vibration suppressor is proposed for relaxing the restricted elevator operation. Finite difference analyses of the rope vibration with/without vibration suppressor are performed. The advantage of using the vibration suppressors for reducing the rope lateral vibration is demonstrated through the numerical calculation : The resonant position of the rope with vibration suppressor is greatly depends on the position of the vibration suppressor. When the vibration suppressors are uniformly installed along full length of the rope, the maximum rope deflection becomes smaller as the number of the vibration suppressor is made greater. It is also presented that the calculated results of reaction force from vibration suppressor are in fairly good agreement with experimental ones.

Dynamic modeling and experiments on the coupled vibrations of building and elevator ropes

This study is concerned with the theoretical modelling and experimental verification of the coupled vibrations of building and elevator ropes. The elevator ropes consist of a main rope which supports the cage and the compensation rope which is connected to the compensation sheave. The elevator rope is a flexible wire with a low damping, so it is prone to vibrations. In the case of a high-rise building, the rope length also increases significantly, so that the fundamental frequency of the elevator rope approaches the fundamental frequency of the building thus increasing the possibility of resonance. In this study, the dynamic model for the analysis of coupled vibrations of building and elevator ropes was derived by using Hamilton's principle, where the cage motion was also considered. An experimental testbed was built to validate the proposed dynamic model. It was found that the experimental results are in good agreement with the theoretical predictions thus validating the proposed dynamic model. The proposed model was then used to predict the vibrations of real building and elevator ropes.

水平・鉛直方向振動を評価可能なエレベータロープモデルの構築

Elevator ropes in a high-rise building are excited by deflection of building caused by earthquake and wind. Especially, the long-period ground motion causes the resonance between elevator ropes and building. As it causes severe damage for elevator, reducing the displacement of elevator rope is demanded. When the rope is long, it is difficult to ignore that the interaction between horizontal and vertical vibrations of rope. Currently, there are some methods to analyze the rope sway. But, the existence of universal method that can analyze the interaction between horizontal and vertical vibrations, and coincide with the experiments using actual elevator rope is very few. Therefore, in this study the new rope model is constructed as a multi rigid body pendulum, and I set the equation of motion by following the multi-body dynamics. And, the coincidence of the proposed model and the result of experiment are shown by numerical simulation. Furthermore, vertical or horizontal direction damping is added at the lower end of rope, and its effectiveness is confirmed.

Lyapunov-Based Control of the Sway Dynamics for Elevator Ropes

In this brief, we study the problem of rope sway dynamics control for elevator systems. We choose to actuate the system with a force actuator pulling on the compensation sheave. Under these conditions, we formulate this problem as a bilinear control problem and propose several nonlinear controllers based on Lyapunov theory to stabilize the rope sway dynamics, for different elevator operation conditions. We present a stability analysis of the proposed controllers, and illustrate their performance via numerical tests.

Lyapunov-Based Control of the Sway Dynamics for Elevator Ropes with Time-Varying Lengths

In this work we study the problem of rope sway dynamics control for elevator systems, with time-varying rope lengths. We formulate this problem as a nonlinear control problem and propose nonlinear controllers based on Lyapunov theory for time-varying systems. We study the stability of the proposed controllers, and test their performances on a numerical example.

111 昇降機システム-ロープ系の地震応答解析に関する基礎的研究

In recent years, due to the increase of the height of the high-rise buildings, elevators become indispensable facilities. Consequently, during earthquakes, as natural periods of a building and an elevator system get close, the movement of the elevator ropes, the compensating ropes and the control cables become important. Moreover, when the ground motion becomes longer, the ropes may hit the wall of the shaft and cause damage to the equipment. In such case, the elevators have emergency stops. However, during the time required for the restoration of the elevators, the building's functions become unavailable. Therefore, to grasp the motion of the elevator's rope during an earthquake is important. Several manufacturers have used this kind of program in order to evaluate the response of their own elevator systems, but comparisons between all these results are difficult. For this research, the aim is to make the analysis program usable by each manufacturer. In this paper, consideration of the sheave mass, the displacement of the elevator's rope of time when cage going up and down is computied by the response of the top of the high-rise building, then examining for the displacement of the elevator's rope during an earthquake.