Design and Modeling of Fluid Power Systems ME 597/ABE Lecture 15

Transcription

1 Systems ME 597/ABE Lecture 15 Dr. Monika Ivantysynova MAHA Professor Fluid Power Systems MAHA Fluid Power Research Center Purdue University

2 Hydrostatic transmissions - Hydrostatic transmission basic principle - Hydrostatic transmission circuit solutions with additional functions - Advanced transmission concepts - Power Split drive technology 2 2

3 Hydrostatic transmission Basic Circuit Design 3

4 Hydrostatic transmission Two variable units controlled in sequence M torque P power V displacement 4

5 Hydrostatic transmission Two variable units simultaneously controlled 5

6 Hydrostatic transmission Pump control manually, with mechanical feedback 6

7 Hydrostatic transmission Pressure limiter Engine 7

8 Hydrostatic transmission Automotive control Engine 8

9 Hydrostatic transmission With electrohydraulic controlled displacement units 9

10 Example Wheel loader Lifting/Tilting Steering 17.4:1 1:1 or 1.4: :1

11 Wheel loader Transmission Design Example Design the hydrostatic transmission for a given wheel loader and calculate the traction force- speed characteristic for the entire speed range. The following parameters and requirements are given: Engine speed: 2200 rpm Engine power: 90 kw Vehicle mass: 10 t Bucket volume: 1 m 3 Density soil: 2kg/dm 3 Dynamic roll radius: m Coefficient of rolling resistance (soil): 0.08 Coefficient of rolling resistance (asphalt): Max vehicle speed (on road): 40 km/h Max traction force: 25 kn 11

12 Axial piston machines Selected pump and motor sizes Max. Displacement Volume Max. Speed Max. Pressure (contin.) Max. Pressure Theoretical flow rpm 100 bar, 1000 rpm Displacement charge pump Mass variable pump 350 bar Fixed displ. motor Mass fixed displ motor Displacement Volume ß=7 Max. ß=7 Mass variable motor 12

13 Trends & New Requirements High traction force & high max. speed Continuously variable transmission (CVT) Reduction of fuel consumption Cost effective 25 mph and more 100,0 kn and more F Z v e v max v 13

14 Transmissions - today Power Shift Gearbox with hydro dynamic torque converter state of the art solution complex, multi-stage gear system high number of clutches low starting efficiency interrupted power flow K1 K2 C/E 14

15 Multiple SICFP 05, June Motor 1-3, 2005, Concept Linköping Zero-adjustable Hydraulic Motor F, β β VM β Pump I II III v unlock 15

16 Power Split Drive SICFP 05, June 1-3, 2005, Linköping Basic structure Ring wheel Satellite carrier Sun wheel additive mode recirculating mode 16

17 Planetary Gear SICFP 05, June 1-3, 2005, Linköping Three wheel planetary gear train Willis equation: When satellite carrier B is block n B = 0 Negative planetary gear, the standing gear ratio i 0AC is negative 17

18 Planetary Gear SICFP 05, June 1-3, 2005, Linköping negative standing gear ratio i 0AC Speed of individual wheels: Directions of rotation of sun wheel A and ring wheel C are different, when the satellite carrier B is blocked! 18

19 Power Split Drive Output coupled System SICFP 05, June 1-3, 2005, Linköping Fendt, Germany, developed a transmission system for agricultural tractors, which is in series production since

20 Power Split Drive SICFP 05, June 1-3, 2005, Linköping Input coupled System Sundstrand Corporation - Responder transmission New development by John Deere 20

21 PSDD SICFP 05, toolbox June 1-3, 2005, for Linköping Simulink POLYMOD allows Precise Loss Models 21 V I n I M I I II n II M II Best Efficiency? P IN n IN n C n A V II n OUT P OUT M IN M C M A M OUT POLYMOD Model Losses M S Losses M S Loss Behaviour Pump & Motor Q S = f(vi, n, Δp) ν = const. 21 M S = f(vi, n, Δp) ν = const.

22 Power Split Drive System Example SICFP 05, June 1-3, 2005, Linköping 22 Development by Claas