1、90 FTM 12Design of New Systems ofControlled Speed Drivesby: Manfred Hirt, Toni Weiss and Peter Boiger, Renk Tacke GmbHL;1,!l,t L,iAmerican Gear Manufacturers AssociationI III Ill!TECHNICAL PAPERDesign of New Systems of Controlled Speed DrivesManfred Hirt, Toni Weiss and Peter Boiger,Renk Tacke GmbHT
2、he Statements and opinions contained herein are those of the author and should not be construed as anofficial action or opinion of the American Gear Manufacturers Association.ABSTRACT:Processes in chemical industries and power plant stations require to a certain extent variable speed drivesof high p
3、ower capacity. In contrast to controlled hydrodynamic or friction clutches a new system ofhydrostatic controlled superimposed planetary gears was developed. Design and calculations as well asefficiency comparisons to other systems will be described. Practical experiences in the drive of large boiler
4、feed pumps will be explained which prove the reliability of these drives.Copyright 1990American Gear Manufacturers Association1500 King Street, Suite 201Alexandria, Virginia, 22314October, 1990ISBN: 1-55589-564-6Design of New Systems of Controlled Speed DrivesManfred Hirt, Toni Weiss and Peter Boige
5、rRENK TACKE GMBHAugsburg, West GermanyIntroductionThe history of speed variation is approx-imately as old as that of the prime mover.Since the speed of a prime mover operatedat the design point is not suitable forevery driven unit, transmissions are neces-sary. This requirement gave rise to thedesig
6、n of a variety of gear configurations:lever cam gears, flexible drives, trans-missions, chain drives, toothed wheelgearing. A unit driven at a given speedcannot meet all the tasks with which it may _be presented. Fig. 2. The operation ofmachine tools, for instance, must be com-patible with the mater
7、ials to be processed.Supplying machinery has to deliverquantities in accordance with their design, _ _vehicles are driven at various speeds.Fig.i: _RECOVAR, controlled speed drive gear unit,built for driving a 2800 MW boiler feedpump, operates in a Finnish peat-firedpower stationSpeed adjustment r i
8、ndispensable for The particular advantage of speed adjust-cost-effective operation ment for energy input is shown by comparingthe trottling of pump delivery. Fig. 3Disregarding solutions where the drive shows the flow loss in a pump which, asspeed is influenced by changing the energy delivery rate r
9、ises, causes an increasingflow (internal-combustion engines, turbo- drop of the p_essure head (i). The lossesmachinery, phase shifting of electric (2) due to wrong admission of the mediummachines), we distinguish between - pulse loss - increase, the more the- actuators on the driven unit or plant op
10、erating condition deviates from theand design point. The reason for this is shownin Fig. 4.- speed control between prime mover anddriven unit.If the volume is throttled at rated speed,backflow occurs, i.e. a certain amount ofThe delivery rate cannot always be variedthe medium delivered circulates at
11、 theby machine-mounted actuators and, if so,only at high expense, for instance, by entry to the wheel The power input re-varying the blading/guide vanes of turbo- quired for this useless vortex is shown onmachinery. This possibility will not be Fig. 3 by area (2).treated in this article.Fig. 2: Lift
12、ing drive for a sluice gate at the river through Augsburg. The small-sizetread wheel serves to provide the necessary breakaway torque. The big wheel is for rapidlifting and lowering of the sluice. This exemplifies a system-tailored adaption of thetransmission ratio in 1644. (Ruckdeschel, Institute o
13、f Technological History, Augsburg)- 2 -40 Pump characteristicsSuppLy quantity l PN_;o;_“_ I / ig. ,ooo, I V iQualitative characteristics of a pump _ _ _ I- ! ! i_ - I I .fFig. 5 exemplifies the power input as a _ 400 YI function of delivery by the pump charac- _ - I _ Powerabso_tionwithn I1_ i vada_
14、e-speed driveand lower performance curve is the poten- _tial saving of power in the case of speed 700 900 1200 1300 1500 1700ad justme nt. SupplyQuantityO (m31h)Fig. 5:Power absorbed by a pump with throttle andspeed control Nornlna quantityn mm = Existin_ technical solutions for speedZ _ _RRetuP_nf_
15、0w_ _. Partial. quantity adjustment=! _q.zcn! i “- “_., Relative speedi In drives offering the possibility ofnge speed adjustment we consider the following=. “-J ROTORSPEiD . I - hydrostatic gears (lower power limits,PartlaL N0mlna therefore without branching off ofspeed speed power - e.g. by means
16、of a superimposedFig. 4: planetary gear train, unsuitable forSpeed triangles of a constant-geometry pump high power equipment)rated speed/rated volume - slip coupling (friction or hydro-(design point) dynamics)-o- rated speed/partial volume(throttled operation) - non-slip planetary superimposed gear
17、ing- partial speed/partial volume(variable-speed operation)- 3 -6 11 7 The constant motor has a fixed relationX speed to flow rate. A variable-stroke pump(2) operates with the constant motor (6)5 8 in a closed hydrostatic cycle. It extractsthe mechanical power required from shaft(i) and feeds it in
18、at shaft (7). Annuluswheel (5) can therefore be driven at vari-4 9 able speed (Fig. 7) counterclockwise10 (enginewise)or clockwise (generatorwise).If it works clockwise (generatorwise) theconstant motor is acting as a constant3 pump and the variable pump is acting as avariable motor. This permits in
19、finitelyvariable speed at the output (i0). Thedifferent operating modes are shown inIII “ “ Fig. 7 and 6._ _ In mode II (maximum efficiency) the annu-2_ lus gear (5) is simply held stationary by_ brake (ii). In this mode the system opera-U_ _ tes as a planetary gearbox with a_,11.1 _%1_fixedgear rat
20、io. In this condition the hydro-1 Sha_ 6 Constant supply pump/motor2 Variablesupplypump/mot0r 7 Shaff-constantsupplyunit statics are inactive and the output (i0)3 Input 8 Intermedi_esha_ operates at a so called base speed.4 Planet carrier 9 Sun pinion5 Annulus 10 Output11 8_akeFig. 6 :Schematic shaf
21、ting arrangement with hydro- Input:static superimposition. Shaft 1 can be planetcarner_equipped with a clutch, shaft 7 with a Output:brake. In the declutched condition and sunpinion“B“Cont_lling:with the brake applied, operation with Annulus“C“high-pressure hydraulic system and the Cauxiliary pump a
22、t standstill is particu- _rolarly economical (cf. also Fig. 7 and 8). “Irange:l-IIIDesign and mode of operation of a planetary . /-_ear unit with hydrostatic superimpositionIn planetary superimposition gearing _Hi H IB (Fig. 6) the planet carrier (4) is drivenfrom the input via shaft (3). The sun ge
23、ar(9) is connected to the output (i0). Arotary motion is imparted on the annulus Fig. 7:gear (5) by the constant motor (6) and the Speed variation at B with constant speedintermediate shafts (7) and (8). at A and superimposed speed at C- 4 -In mode I (speed increase, Fig. 7 and 8) A look at efficien
24、cypower is fed into the hydrostatic circuitthrough shaft (i) and the constant motor The following simplified analysis of effi-system (6) with the intermediate shafts (7) ciency shows the significant advantages ofand (8) is activated. Speed increase is by superimposition gearing. Auxiliary powerrotat
25、ing the outer central wheel (5) in as is, for instance, required for lubrica-contrary direction to the driven planetary ting oil supply, has not been taken intocarrier, account in these equations.In mode III (speed reduction, Fig. 7 and 8) As with any coupling subject to slip thepower is extracted f
26、rom the annulus wheel formula shown in the table 1 applies also(5). The annulus wheel rotates with the to the hydrodynamic-gear control-coupling.planetary carrier. The power taken off isrefed into the drive power through theintermediary shafts (8) and (7), thehydrostatic circuit and shaft (i).nma x
27、- nabPv = ( “Mab) + (l-_s)Pab + PK9550OperatingmodeIm0t0PWlSe hydraul, losses mech. lossesthereforeMabPv = 9550 (nmax _S nab) + PK (i)InputP P - A P OutputPOperatingmode II. neutral Table1 :Power loss in the large-size hydraulic _ I gear control couplingThis power loss has to be dissipated byInputP
28、OutputP the transmission fluid.Conditions are more complicated in theOperahng mode 111generatorwisecase of the superimposition gear unit. Adistinction is made between operationabove the base speed nO (mode I, table 2)and operation below the base speed n O(mode III, table 3)InputP P . A P OutputPFig.
29、 8:Power flow in the superimposition gear unit For explanation of symbols see table 4- 5 -Pv = (I-_G) (Pab-PH)+ (i-_) PH + (I-_s) PH (2)mech. gear losses in the mech. losses inlosses hydrostatic the superimpositioncircuit drive(nO - nab) Mabwith PH= (2a)_S 9550Table 2: Power loss in a superimpositio
30、n gear unit above base speedPv = (I-_G) (Pab+PH) + (I-_u) PH + (I-_s) PH (3)mech. gear losses in the mech. losses inlosses hydrostatic the superimpositioncircuit drive_S (n0-nab) Mabwith PH = (3a)9550Table 3: Power loss in a superimposition gear unit below base speedMab Nm output torquenan i/min dri
31、ving speednab i/min output speed in the condition considerednO I/min base speed (output speed at which the annulus wheel is at standstill)nmi n i/min minimum output speed requirednma x i/min maximum output speed requiredPab kW output powerPH kW superimposed power at annulus wheel of planetary stageP
32、K kW vortex losses on outside of coupling, etc.Pv kW power dissipationqG - efficiency of drive train, comprising possible cylindrical gearcountershaft and planetary gear (approx. 97,5 %)_S - efficiency of cylindrical gear stages (approx. 99 %/stage)_U - eff. of superimposed machinery. Hydrostatic su
33、perimposition: 75 % maxTable 4: Explanation of symbols used- 6 -Considering the above approaches in quali- 125fltative terms reveals: In the slip coupling 1204|the entire transmission output is subject 1154Ito losses which increase the more the 110Ildriving speed deviates from its maximum 1054(Table
34、i). 100- HighpressuPe95 - hydraulicsPM“(1-no)In case of the superimposition gear, the 90situation differs. This gear has its 85-optimum efficiency at the base speed nab = 80no since here PH = 0. (Tables 2 and 3) 75-_70.Base speed is selected on the strength of c 65- AuxlUaryeconomic considerations a
35、ccording to the o9 60- pumpso9operating requirements of the drive, o. 55- Superimposeddrive5o- P(1-_,lMost of the power output is transmitted _ 45- 0ufputshaftQ- _Economywith small losses of the very efficient 40- operatlorgear transmission. In addition, there are 35-only insignificant mechanical lo
36、sses in 30- PlanetaPystagethe closed superimposition system. (Tables 25- _2 and 3). The design permits disconnecting 20-the hydrostatics so that the machine can be 15-CyLindricalused as a straightforward planetary gear I0- geaPstageunit. 5-tube oil pumpI I I I 1 I I I4200 _ ,._. 4500 _ 5000 _ 5300 1
37、/miniHigher or lower speed require a certain _ _“o_= _ _ OUTPUT SPEED, superimposition power PH subject to theloss (I-_)PH this power being by far thesmaller part of the power transmitted. The Fig. 9:set of curves showing the power loss can Losses in a RECOVAR-Type REV 50 gear unitbe drawn on the st
38、renght of test bench measured on the testrig a 20 % rated loadruns (Fig. 9). and projected to full loadThe losses due to “auxiliary pump“, “super-imposed drive“, “output shaft“, “planetary volume delivered and the oil pressure instage“, “cylindrical-gear stage“ and the hydrostatic system increase as
39、 the“lubeoil pump“ are only to a limited difference to the base speed (n0) growsextent a function of load or speed. It larger.should be noted that in the case conside-red, i.e. a boiler feed pump with an Fig. i0 gives a comparison of the lossesoutput of 2.8 MW, the required mechanical involved, on t
40、he one hand calculated forpower input depends very much on the speed, the hydrodynamic gear control couplingprovided as stand-by, on the other handHigh-pressure hydraulic systems being for the hydrostatic superimposed planetaryhighly dependent on the driving speed, gear.cause losses of up to 50 % si
41、nce the oil- 7 -POWER On the basis described above, speedLOSS : adjustment is particularly suitable for(k_Hydrodynamic the drive applications shown on table 5.-gear control-400 -_ coupling .Superimposed planetary gears in mobileapplicationsIn 1943, RENK started off with the design300 of steering tra
42、nsmissions for trackedvehicles. So superimposed transmissionswith hydrostatic drive there have a long21 tradition. It was, in particular, the_ hydrostatic system which had to be deve-_i, _I loped to provide high reliability. At200_, _I -_: =_ _ times, RENK even constructed the hydro-_! _: El static
43、system itself., I100 , iECOV 50Gear unit withhydrostatic superimposition I Fig. 10 :(measurementsattestrig),i Comparision of power losses in a hydro-i dynamic gear coupling and a hydrostaticIi superposed planetary gear unit at the same, i h j“ , , I J operating conditions4000 5000PUMP SPEED l/miniSp
44、eed/output Field of application Power Gear unitrelationship capacity typeNone Power generation at fluctuating propulsion 400 kW RCF(n = constant) speed of a marine Diesel engine toWind-driven turbine, 2600 kWTidal power station, Water power stationP = f (n) Conveyor machinery 1 kNm RECOVARScrew-type
45、 and reciprocating compressors toTorque-biasing transmisson for testbenches 100 kNmfor testbenchesP = f (n2) Comminuters 1 kNm RECOVARAgitators toMixers 100kNmp = f (n25“3) Centrifugal pumps 500 kW RECOVARCentrifugal compressors to1000O kWTable 5: Field of application for speed adjustement with pote
46、ntial saving- 8 -_ IL II _“_ Constant motorJFig. ii: Closed hydrostatic circuit with major components: variable-delivery pump,constant-speed motor, flushing block, delivery volume controllerv IFig. 12: The RCF gear unit with the generator is flanged to the prime mover. A so-calledcrankshaft gear con
47、nects chrankshaft and RCF gear unit- 9 -A 60-ton armoured vehicle can now be the engine speed, which differs dependingsteered with as little effort as a passen- on the operating mode, into a constantger car equipped with servo-steering, generator speed (Fig. 12). Since 1982 over140 gear units were p
48、roduced (Fig. 13) andFar more than i0000 of such superimposed sold, approximately 100 of them are ingear units with outputs of up to 1300 kW operation. Their average service time perare presently delivered, year is 5000 hours. It is the combinationof a mechanical gear box together withThe wide exper
49、ience gained with closed “Control and monitoring electronics“hydrostatic drive circuits (Fig. ii) gave developed and produced in one hand at therise to continuous upgrading of the compo- gear maunfacturer and the use of hydraulicnents until a standard was reached which actuators for the circulating oil volumealso permitted application in continuous of the hydrostatic circuit, which haveindustrial service. For economic power made it possible to engineer a highlygeneration on board of ships with slow
