Importance of Thermal Balance for Hydraulic Elevators

摘要

Heat generation of hydraulic elevator power units is a very important phenomenon and should be kept under control for good ride performance and longer service life. Very low and very high oil temperatures decline ride quality of the elevator. Very low oil temperatures cause sluggish behaviour of control valves and may also lead to cavitation problem whereas, high oil temperatures, apart from declining travel performance, deteriorate lubricating properties and increase contamination level. If it is not cared, a cyclic heat generation process develops, which decreases component life, results in frequent servicing and increases annual cost of the elevator. A true power unit design should consider thermal balance of the elevator at an acceptable oil temperature as one of the main design constraints. In most cases, coolers can be avoided by a proper design, which reduces energy consumption accordingly. In this paper, thermal balance temperature of hydraulic elevators is assessed with respect to type of elevators, suspension ratio and various environmental conditions through a derived theoretical model. Recommendations to achieve lower balance temperature for hydraulic elevators are also given.