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EN
The paper describes a new approach to the issue of controlling an indirect elevator with a bidirectional variable-speed pump and a simple controller based on the position sensor. The aim of this paper is to present a method of controlling the speed of the elevator to ensure smooth movement and proper positioning of the car on the foor, regardless of its load and ropes rigidity. The main feature of the proposed solution is the use of a frequency inverter in vector mode to control the speed of the car in both directions. The control function is based on virtual cams comparing actual measurements from the car position sensor. The proposed control strategy has been experimentally verified on the existing indirect elevator drive, and the obtained results indicate a very high accuracy in maintaining and shaping the speed and positioning of the car. The conducted research confirms the possibility of using a new method of controlling hydraulic and indirect elevators. The benefits of this method include a less complex hydraulic system, the control of overloads in the car and vibrations in the rope system, and the possibility of energy recovery.
EN
This paper describes investigation on the influence of hydraulic oil temperature on the performance of a hydraulic pump. The aim of the research is to determine changes in volumetric efficiency of the pump in the form of maps of operation at different temperatures of the hydraulic oil, in conditions of variable speed and pressure. The described tests were carried out on an experimental stand with a hydraulic fixed-displacement gear pump controlled by a servo motor. Based on the signals from the sensors processed with the LabVIEW program, maps of the hydraulic pump operation were drown in a wide range of speeds and temperatures. The paper presents the results of the research and based on this the conclusions regarding the main aim of the research and others that were observed during the measurements were presented. The most important conclusion from the study shows that the temperature-dependent characteristics provide users with a significant amount of information such as operating conditions that will ensure a high level of efficiency.
EN
The article presents the numerical investigation of the overhead crane’s energy consumption. The analysis is based on the hybrid model of the crane consisting of numerical model of drive mechanisms as bridge, trolley, hoist and also experimentally measured power consumption of each control unit. The numerical model was verified experimentally on the real crane. The investigation focuses on analyzing the energy consumption of the overhead crane in relation both to the travelled distance and also for the lifting and lowering heights of a suspended payload. Particular attention was paid on the cases straightly related to the hoist, as a main factor of improvements in the energetic efficiency of the overhead crane. Energy consumption was investigated for a variety of magnitudes of transported mass.
PL
W artykule przedstawiono badania symulacyjne energochłonności pracy suwnicy pomostowej. Podstawą badań jest model hybrydowy bazujący na numerycznych modelach mechanizmów mostu, wózka i wciągarki oraz na eksperymentalnie zmierzonym zapotrzebowaniu mocy dla układu sterowania. Model numeryczny został zweryfikowany na rzeczywistej suwnicy. W pracy przedstawiono analizę energochłonności mechanizmów jazdy w zależności od pokonanej drogi, jak również mechanizmu podnoszenia w zależności od wysokości podnoszenia i opuszczania ładunku. Zwrócono szczególną uwagę na mechanizm wciągarki, jako na główny czynnik poprawy efektywności energetycznej. Energochłonność została zbadana dla różnych mas transportowanego ładunku.
EN
The article describes a new approach to the issue of controlling hydrostatic systems with fixed displacement pump using the frequency inverter and the simple controller unit. The aim of the article is to present a method of controlling the velocity of scissor lift drive to provide a constant velocity of the platform, regardless of its load, geometry and current location. The main feature of the proposed solution is the use of feedback in the quasi open loop from platform displacement sensor to the velocity control system of the electric motor. To ensure theThere is a possibility of using the proposed control system in a typical hydrostatic scissor lift, with added only an inverter, a platform displacement sensor and a controller to an existing machine. The proposed control strategy has been verified experimentally on an existing drive, and the obtained results show satisfactory mileages and very high accuracy of maintaining and shaping the platform velocity. The developed mathematical and physical models of the whole drive has been verified on the test bench. The conducted research gives information about new possibilities of using the inverter in hydrostatic systems, such as increasing efficiency, decreasing acceleration, decelerations , damping and improve the safety of the operation.
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