Experimental research on energy losses through friction in order to increase lifetime of hydraulic cylinders

Abstract

Abstract. Starting from some theoretical considerations, the article presents some experimental results on the assessment of dry and viscous friction forces that occur in the operation of hydraulic cylinders, the basic elements from the structure of hydraulic drive systems. It also presents some specific aspects regarding the durability of the seals of hydraulic cylinders, in order to increase lifetime of hydraulic cylinders, respectively lifetime of hydraulic drive systems. IntroductionAs it is known, improving energy efficiency of industrial machinery and equipment is a constant direction of activity for researchers and manufacturers of such products. On this line, a couple of theoretical and experimental research activities have been developed in order to find new technical solutions for driving, and also to assess/quantify their effects in terms of energy, with a goal to improve efficiency of various drive systems. Such research activities have also been conducted for hydraulic and pneumatic drive systems (Fluid Power systems), and the results obtained were very good, especially in cases when electronic control and adjustment systems have been comprised in the hydraulic actuators, this meaning also applying information technology in drive processes and developing intelligent hydraulic drive systems. To improve energy efficiency of hydraulic drive systems, an important direction of action was to increase energy efficiency of each individual component, targeting a decrease in fluid flow and pressure losses, in energy losses, generally speaking, and correspondingly targeting increased efficiency rates and prolonged life span of components.One of the most important components of hydraulic drives is represented by hydraulic drive motors, which convert hydrostatic energy into mechanical energy. There are three types of hydraulic motors, namely: linear, rotary and reciprocating hydraulic motors. This paper discusses issues concerning the linear hydraulic motors, also generically known as "hydraulic cylinders" and presents some experimental research activities conducted in the institute INOE 2000-IHP in Bucharest, Romania, aiming to assess the total energy losses in the operation of a hydraulic cylinder and increase the life span of these components. These total energy losses include viscous friction losses occurring on fluid flow [1], friction losses that occur in the hydraulic cylinder rod seal [2], friction losses that occur in the hydraulic cylinder piston seals [3] and [4], and also dry (or Coulomb) friction energy losses in rod and piston guides.An important part in increasing the life span of the hydraulic cylinders is played by durability of sealing systems, which are the first causing decommissioning of hydraulic cylinders.

Scaling Orchestration in Physical Model Test of Oscillating Buoy Wave Energy Converter

“…The regulation methods in the second-stage part are listed as follows: (1) The accurately controlled components of hydraulic PTO device, including the hydraulic cylinder, accumulator, valves group, and hydraulic motor, etc., should be used in the model test to realize the accurately controlled PTO force to satisfy the similarity requirement (Henderson, 2006;Josset et al, 2007). (2) The energy loss in the hydraulic PTO device includes the viscous friction loss of fluid and the friction loss between components (Cristescu et al, 2016(Cristescu et al, , 2017. The model test calibration method is suggested to keep the power loss similar in the prototype and scaled model, and the calibration results would directly influence the accuracy of model test results.…”

Structural Design and Dynamic Characteristics of Overloaded Horizontal Servo Cylinder for Resisting Dynamic Partial Load

“…To satisfy the high-precision control requirements for position, velocity, and force, the ability of the servo cylinders to overcome the influence of partial load on sealing performance and friction loss under heavy-load, high-speed, and high-frequency responses is a key design consideration. Figure 2 presents a photograph of a servo cylinder [5,24].…”

Tribological Properties of Hydraulic Cylinder Piston Sealings in Water and Oil Hydraulics

“…Based on the acoustic emissions, they can distinguish between perfectly worn seals, moderately worn seals, and unworn seals. In the work of Cristescu et al [13], an experimental investigation of piston friction force was carried out seals in hydraulic cylinder. They tested a type of seal, the U-seal.…”