Microsoft PowerPoint - HydL_Ch7_Motors [호환 모드]

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1 7. Hydraulic Motors Operation of hydraulic motors Limited rotation hydraulic motors Gear motors, Vane motors, Piston motors Torque & power delivered by hydraulic motors Performance of hydraulic motors Comparison of variable performance factors of hydraulic motors Analysis of the operation & performance of hydrostatic transmission -1-

2 7.1 Application of Hydraulic Motors -2-

3 7.2 Limited Rotation Hydraulic Motors -3-

4 Analysis of Torque Capacity R R = outer radius of rotor (in, m) R V = outer radius of vane (in, m) L = width of vane (in, m) p = hydraulic pressure (psi, Pa) F = hydraulic force acting on vane (lb, N) A = surface area of vane in contact with oil (in 2, m 2 ) T = torque capacity (in.lb, N.m) F = pa= p( R R ) L V R ( RV + RR ) T = p( RV RR) L 2 pl T = ( RV RR ) VD = π ( RV RR ) L 2 pv T = D 2π = [m3/rev] -4-

5 Applications of Rotary Actuators -5-

6 7.3 Gear Motors -6-

7 Gear Motors 구조는기어펌프와거의동일 탱크로연결되는드레인 (drain) 라인이있다. 장점 단점 구조간단 값이싸다 유압유중의이물질에의한고장이생기기어렵다. 가혹한운전조건에비교적잘견딜수있다. 누설유량이많다. 토크변동이크다. 베어링하중이크므로수명이좀짧다. -7-

8 7.4 Vane Motors -8-

9 Vane Motors with Spring-loaded Vanes -9-

10 Vane Motor 구조는베인펌프와거의동일링에베인이밀착하도록클립 ( 스프링 ) 으로밀어대는구조를갖고있다. 장점 단점 구조가비교적간단토크변동이적다. 베어링하중이작다. 메인끝단이나캠링면이마모되어도누설이크게증가하지않는다. 누설유량이비교적많다. 베어링과캠링의마모가크다. 기동시나저속시토크효율이낮다. -10-

11 7.5 In-Line Piston Motors (Swash Plate Design) -11-

12 Operation Principle of Piston Motor -12-

13 Two Configurations of In-line Piston Motors -13-

14 Axial Piston Motors (Bent-axis Design) -14-

15 Variable Displacement Bent-axis Piston Motor -15-

16 Piston Motor 장점 단점 누설이적다. 저속안전성이우수하다. 회전속도범위넓다. 효율높다. 수명길다. 구조가복잡하다. 고가이다. 레이디얼피스톤모터 구조상배제용적을크게할수있고, 저속대토크용으로사용한다. 일반적으로 HTLS(High Torque Low Speed) 모터로불리운다. -16-

17 7.6 Hydraulic Motor Torque, Power, and Flow-Rate Theoretical torque: torque that a frictionless hydraulic motor would deliver T T ( N m) = V m rev p Pa 2ππ 3 D ( / ) ( ) Theoretical power Power ( W ) = T ( N m ) N ( rad / s ) T 3 D ( / ) ( ) ( / ) V m rev p Pa N rad s = 2π Theoretical flow-rate Q m s V m rev N rev s 3 3 T( / ) = D( / ) ( / ) -17-

18 7.7 Hydraulic Motor Performance Volumetric efficiency theoretical flow rate motor should consume Q η T v = = actual flow rate consumed by motor Q A = Q T Q T + ΔQ Mechanical efficiency actual torque delivered by motor η m = = torque motor should theoretically deliver T T A T = TT ΔT T T T T 3 VD ( m / rev) p( Pa) ( N m) = TA( N m) = 2π actual wattage delivered by motor Nrad ( / s) Overall efficiency η = ηη = o v m actual power delivered by motor actual power delivered to motor -18-

19 Hydraulic Motor Performance - 보충 배제용적 V D [m3/rev] 회전수 N [rev/s] 이론공급유량 Qth = V 모터내외부누설유량실제공급유량 Q = Qth + Q l m N Q l 이론발생토크 마찰부하토크 실제유효토크 기계효율 η m T = th T f pv m 2π T = T th T f = T T th 체적효율 η = v Q th Q 이론동력 공급동력 실제발생동력 Lth = pqth = T L in = pq L out = T N th N p, Q l Q T f T, N 전효율 L out L in η = =η η v m -19-

20 Performance Curves for Variable Displacement Motor -20-

21 [ 예제 1] 유압모터의효율과동력 유압펌프와유압모터로구성된구동장치가있다. 펌프쪽전동기는회전수 2000rpm, 8PS의동력이소요되고있다. 2 펌프의토출압 p= 70 kgf / cm, 토출량 Q=45 45lpm 이다. V D 유압모터의배제용적 = 40cc/rev, 효율 =90% 이다. m η v M η = 2000rpm, 8PS p, Q T, N load (1) 유압펌프의기계효율, 전효율 (2) 유압모터축의유효토크, 회전수를구하라. η [ 답 ] (1) η = 92.1%, o m = 87.5% (2) T= kgf cm, N = rpm -21-

22 Control of Hydraulic Actuator Valve controlled actuator Hydraulic Power Source Power Control Devices Hydraulic Actuators Pump controlled actuator Hydraulic Power Source Hydraulic Actuators Self controlled actuator Hydraulic Power Source Hydraulic Actuators -22-

23 Control Method of Hydraulic Actuator Valve Controlled System Command Controller Servo valve Position Transducer Pump Controlled System Servo valve Motor Position Transducer Cylinder Command Controller -23-

24 Pump Controlled Motor System HST(Hydrostatic Transmission) 의유형 HSTs : hydrostatic transmissions ping term Pi Open circuit Discontinuous flow (interrupted) Closed circuit Continuous flow (uninterrupted) Control term Open loop Closed loop Open loop Closed loop No feedback Feedback No feedback Feedback Transducer Command T o N o Transducer Command T o N o To N o T o N o -24-

25 Hydrostatic Transmission System (HST) -25-

26 Closed-Circuit / Closed-Loop HST In-line single unit HST Inlet port Torque limiting valves psi 50 psi Low pressure relief valve (make up oil) Pre-charge pump Bypass valve Case drain -26-

27 Advantages of HST 빠르고정확한무단변속과제동속도 / 토크의작동범위가넓다과부하시손상이없다설계와장착의유연성이크다관성과토크가큰고출력에적합 부하와속도의변화가심할때기계식변속장치보다적합 open circuit HST 속도와토크가한방향오버런닝시캐비테이션발생사용범위가제한양방향펌프와모터장착보조부품추가 - 유량보충밸브 - 플러싱밸브 - 체크밸브 closed circuit HST 장점의극대화 -27-

28 Characteristics of HST -28-

29 [ 예제 2] 가변용량형펌프 + 가변용량형모터조합 HST V p 펌프규격 : 배제용적 = 0~80 ml/rev 체적효율 η pv = 85% 전동기규격 : 회전속도 N = 1000 rpm 전효율 η = 89% 모터규격 : 체적효율 = 93% η mv η mm 기계 ( 토크 ) 효율 = 87% 펌프-모터간고압쪽관로 : 8bar 마찰손실모터를제외한 HST의전효율 η = 60% 위의조건에서, 펌프용량이최대값의 50% 에서구동하고유압모터축에 12KW가가해졌을때 (1) 펌프토출압 (2) 보충펌프유량 (3) 릴리프밸브가동작하기전까지가할수있는가능한부하증가율 (4) 유압모터가최소속도 200 rpm으로작동할때, 모터최대용량 (5) 전기모터에의공급동력 (6) 펌프의기계효율을구하라. M set at 270 bar Load Q 1 [ 답 ] (1) 255 bar (2) ml/s (3) 6.1 % (4)167 ml/rev (5) 22.5 KW (6) 85 % -29-

30 [ 예제 3] 가변용량형펌프 + 정용량형모터조합 HST 펌프규격 : 배제용적회전속도누설유량계수 모터규격 : 배제용적 V p ϖ p C p η pt V m C m = 0~164 ml/rev = 25 rev/s = 0.9 ml/bar s 토크효율 = 85% 누설유량계수 = 65 ml/rev = 0.9 ml/bar s 기계 ( 토크 ) 효율 = 85% mm 모터축관성부하 = 1.0 m p, Q ϖ ϖ p m m η M load 2 J kg m 위의조건에서 (1) 펌프용량이최대값의 60% 에서구동하고유압모터가 ϖ m = 33 rev/s 일때, 유압모터의가속도 (2) (1) 의조건에서전동기의출력 (3) 펌프용량이 0 에서최대값의 50% 의계단입력을가할때, 모터축의정상상태속도의 63% 에도달시간을구하라. 2 [ 답 ] (1) 156 rad / s (2) 51.4 KW (3) s T, N J -30-

31 Application of Actuator Control System-1 NC Machine position control system Servo valve Hydraulic motor Work table Hydraulic pump - + Command Ball lead screw Position Transducer -31-

32 Application of Actuator Control System-2 Tension control system for Paper making processes Roll Web Hydraulic motor - + Command dancer roll Position Transducer -32-

33 Application of Actuator Control System-3 Web guiding system for Paper making processes Main roll Guide roll Photoelectric cell & Light source Deviation Adjusting cylinder - + Command Servo valve -33-

34 Application of Actuator Control System-4 Thickness control in Rolling processes Screw Backup roll Load cell Strip Working roll Thickness gauge Backup roll Position Detector Automatic Gauge Controller -34-

35 Advanced Actuator - 1 Servo-actuator (hybrid actuator) servovalve 내장, 또는 valve spool 에 step motor 부착 displacement transducer 내장 ultra-low friction hard wearing sealing fatigue testing ti m/c 등의 precision i control system 용 -35-

36 Advanced Actuator - 2 Intelligent cylinder counter 를이용한 digital position transducer 부착 stroke범위내 set point를자유롭게지정, variable switch로서사용 servovalve 또는 proportional valve 를내장하여위치 / 속도제어시스템의통합요소로사용 -36-

37 Report Text Problems Due date: 2 주후 -37-

Microsoft PowerPoint - chap633.ppt [호환 모드]

Microsoft PowerPoint - chap633.ppt [호환 모드] 제 6 장액츄에이터 6-1 제 6 장액츄에이터 6.1 유압실린더 6.2 유압모터 6.3 Hydrostatic Transmissions 6.4 액츄에이터제어시스템 6.5 액츄에이터의최근동향 제 6 장액츄에이터 6-2 액츄에이터 (Actuator) 의기능상분류 실린더 Linear Actuator 피스톤형 램형 액츄에이터모터 Rotary Actuator Fig.