MEC-E5004 Fluid Power Systems
Research Assignment 1
RESEARCH ASSIGNMENT CONSISTS OF A LABORATORY EXERCISE AND SOME RESEARCH PROBLEMS TO BE SOLVED. THIS DOCUMENT CONTAINS THE TASKS FOR BOTH PARTS OF THE ASSIGNMENT.
The Research Assignment contains several research problems, that are solved using information gathered in lectures and laboratory exercise, and found in study material and especially in other literature, library databases, research reports, conference and scientific papers, component, apparatus and fluid manufacturers’ web-pages, etc. To assist in seeking information the research problems are joined with some exemplary headwords, but it is advisable to use also other suitable words.
The aim of working with these research problems is that by processing the information you find in several different sources you are able by your own personal thinking to create a more comprehensive personal understanding of the subject at hand than is presented in any of the individual sources. Especially valued in the answers to the problems is particularly bringing forward your own and justified viewpoint and learning on the subject. Also appreciated is to use illustrative and in terms of text essential picture material (e.g., phenomena visualizing, application examples) to support your writing. In assessing the answers these matters are taken into account to the extent that earning points over 80 % of the problem-specific maximum requires indicating ability to use external learning material in a way that indicates good understanding of the subject and ability to differentiate essentials from the non-essentials. If the essential illustrative picture material is missing from the answer, the maximum possible amount of points to be earned from this answer is 70 % of the prob-lem-specific maximum points.
Appropriate length of answer to each research problem is 2‒2,5 pages including picture material the length of pure text being 1‒1,5 pages. The font used in answers is either 10 pt Arial or 12 pt Times New Roman. In assessing the answers the most crucial is their contents and quality, not their length. So strive to write concise, consistent and of content comprehensive answers!
Note: Each answer must also include a list of references that is added to the above defined length of answer increasing it with about a half of a page. Appropriate number of references per answer is 3‒4 at least, and, Wikipedia is not accepted.
NOTE: Research Assignment 1 Report must be submitted 24.10.2016 at 12:00 o’clock the latest. File is submitted via course’s MyCourses -page.
File format either word of pdf.
NOTE: Reports without official Cover Page are not accepted!
Cover Page is downloadable from the MyCourses -page.
A. Laboratory Exercise
Aim of this exercise is to familiarize oneselves with measuring quantities related to hydraulic systems and using measured data to define the characteristics of hydraulic components. Also the factors affecting to the reliability and uncertainty of measured and calculated data will be studied. A manu-ally operated 4/3 directional control valve and an electricmanu-ally controlled 4/3 proportional directional control valve are used as example cases.
Hydraulic fluid of the measurement system
Neste Hydrauli Basic 46
Density (15°C) 865 kg/m3 Viscosity ( 100°C) 7,9 cSt Flash point (COC) 222 °C Viscosity ( 40°C) 46 cSt
Pour point -42 °C Viscosity ( -10°C) 990 cSt
Viscosity Index 142 Viscosity ( -20°C) 2940 cSt
20 -1 -10 0 10 20 30 40 50 60 70 80 90 100 10 100 1000 10000 n [cSt] q [°C]
Figure 1. Temperature dependence of Neste Hydrauli Basic 46.
Fluid temperature in measurements: ______°C → Viscosity: _______cSt Measurement data files for both measured valves can be found in the course’s MyCourses -page after the exercise (see under Exercises and Research Assignment 1). The data and the above pre-sented characteristics of hydraulic fluid are used in solving the research problems (both in Research Assignment 1 and Research Assignment 2). The contents of the measurement files are described on the next page.
Measurement files
The files contain the measured quantities in following column order and units:
pAB [bar] pP [bar] pT [bar] qV [l/min] U [V]
pAB = pressure at valve ports A and B
pP = pressure at valve port P
pT = pressure at valve port P
qV = volume flow through the valve
U = control voltage of electrically controlled 4/3 proportional directional control valve
Measurement files are:
Directional_Control_Valve_PABT.lvm : manually operated 4/3 directional control valve, flow directions P→A, B→T
Directional_Control_Valve_PBAT.lvm : manually operated 4/3 directional control valve, flow directions P→B, A→T
Proportional_Control_Valve_10bar.lvm : electrically controlled 4/3 proportional directional control valve, flow directions P→A, B→T and P→B, A→T, pressure difference over the valve (P→T) 10 bar Proportional_Control_Valve _100bar.lvm : electrically controlled 4/3 proportional directional
control valve, flow directions P→A, B→T and P→B, A→T, pressure difference over the valve (P→T) 100 bar
B. Research problems
In answers the quantities have to be presented in following units:
pressure [bar] velocity [m/s] force [N] power [W]
volume flow [l/min] position [m] torque [Nm]
B.1 This problem is related to the manually operated 4/3 directional control valve studied in the Laboratory Exercise
a) Draw the characteristic curves diagram of this valve depicting the pressure losses of each flow channel (P→A, B→T, P→B ja A→T) as a function of volume flow.
b) Using the characteristic curve of flow direction P→A as basis solve how would the pressure loss – volume flow dependence for this flow direction be if the temperature of the hydraulic fluid would have been 0 °C or 60 °C during measurements (the kinematic viscosity of the fluid for these temperatures can be defined from Fig. 1). What conclusions can be drawn on the effects of the fluid temperature on the characteristics of hydraulic components and systems? How does the fluid temperature affect to the reliability and comparability of the measured quantity values?
c) Assume that only one operating point (a pressure loss at a certain volume flow) of the characteristic curve of flow direction P→A is known. Solve the curve computationally for the whole measured volume flow range when the only known operating point is I) the first point, II) the middle point and III) the last point of the measurement file. Draw the three computed characteristic curves to the same diagram with the measured P→A characteristic curve. What effect does the as calculation basis used operating point have on the accuracy and reliability of computed characteristic curve? Are there any differencies between the curves, and if there are, where do they (may) result from?
B.2 The problem that has been selected for you to answer from the problems listed below is announced in the Course Score Table for the current Study Year found in the MyCourses -page (see Results).
a) How does the replacing of the multi switching position valves (e.g., 4/3 directional control valves) with two position logic valve elements change the designing and realizing of hyd-raulic systems? What benefits and challenges does this change from one valve technology to another entail, and in which kind of applications this change results into considerable advantages?
Exemplary headwords: cartridge valve, logic element technology
b) How does the replacing of traditional valves and pumps with digital hydraulic components change the designing and realizing of hydraulic systems? What benefits and challenges are related to digital hydraulic systems, and in which kind of applications this technology would benefit the system and its characteristics considerable?
Exemplary headwords: digital hydraulics, digital fluid power, digital cylinder, digital pump, digital pressure accumulator
B.3 The problem that has been selected for you to answer from the problems listed below is announced in the Course Score Table for the current Study Year found in the MyCourses -page (see Results).
a) Explain the connection types of mobile directional control valves (parallel, series, etc.): structures, pros and cons, special characteristics of different connection types?
Exemplary headwords: parallel, serial/tandem, priority connected mobile valves
b) Explain the structures of mobile valves (monoblock valves, sectional valves, decentralized valves); structures, pros and cons, special characteristics of different connection types? Exemplary headwords: monoblock, sectional mobile valves
B.4 What kind of consequences does an energy regeneration function have to a hydraulic system when implemented in it, and what kind of demands does a profitable energy regeneration set to a hydraulic system and the components used in it? What kind of components or component types are typically used in regenerative hydraulic systems, how the energy is recovered and utilized? In which kind of applications the implementing of energy regeneration most likely produces good results, i.e., what are the prerequisites for an effective energy regeneration? Exemplary headwords: energy recovery, recuperation, energy efficiency
B.5 The problem that has been selected for you to answer from the problems listed below is announced in the Course Score Table for the current Study Year found in the MyCourses -page (see Results).
a) What are the reasons for using water as a hydraulic fluid in some high-pressure hydrostatic systems, and in which kind of applications water is typically used? What kind of demands does the water set for the system and its components, and which are the main differencies between water hydraulic and oil hydraulic components?
Exemplary headwords: water hydraulics
b) What advantages and challenges are related to hydraulic systems based on magnetorheo-logical fluids considering their characteristics, control, performance and also the compo-nents and fluid used in them? For which kind of applications the magnetorheological are especially suitable?
Exemplary headwords: magnetorheological technology, MR technology
B.6 The theme that has been selected for you to explain from the themes listed below is announced in the Course Score Table for the current Study Year found in the MyCourses -page (see
Results).
Themes:
a) Valve control
b) Pump control in general
c) Displacement control of pumps d) Speed control of pumps
e) Secondary control
What advantages and challenges are related to the control type considering different appli-cations?
Exemplary headwords: valve control, pump control, displacement control, speed controlled pump, secondary control, actuator control
