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

Abstract

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.