Monika Ivantysynova 4 Design and Modeling of Fluid Power Systems, ME 597/ABE 591Hydrostatic transmission Two variable units –controlled in sequence M… torque P… power V… displacement...
Trang 2© Dr Monika Ivantysynova 2 Design and Modeling of Fluid Power Systems, ME 597/ABE 591
Hydrostatic transmissions
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- Hydrostatic transmission – basic principle
- Hydrostatic transmission – circuit solutions with additional functions
- Power Split drive technology
- Advanced transmission concepts
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Basic Circuit Design
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Hydrostatic transmission
Two variable units –controlled in sequence
M… torque P… power V… displacement
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Two variable units – simultaneously controlled
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Hydrostatic transmission
Pump control – manually, with mechanical feedback
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Engine
Pressure limiter
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Engine
Hydrostatic transmission
“Automotive” control
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With electrohydraulic controlled displacement units
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Example Wheel loader
Steering Lifting/Tilting
1:1 or 1.4:1 17.4:1
17.4:1
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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:
Dynamic roll radius: 0.617 m
Coefficient of rolling resistance (soil): 0.08
Coefficient of rolling resistance (asphalt): 0.015
Max vehicle speed (on road): 40 km/h
Max traction force: 25 kN
Example
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Axial piston machines
Selected pump and motor sizes
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• High traction force & high max speed
• Continuously variable transmission (CVT)
• Reduction of fuel consumption
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Transmissions - today
Power Shift Gearbox with hydro
dynamic torque converter
C/E
K1 K2
• state of the art solution
• complex, multi-stage gear system
• high number of clutches
• low starting efficiency
• interrupted power flow
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Zero-adjustable Hydraulic Motor
Trang 16SICFP’05, June 1-3, 2005, Linköping
© Dr Monika Ivantysynova 16 Design and Modeling of Fluid Power Systems, ME 597/ABE 591
Power Split Drive
additive mode recirculating mode
Basic structure
Ring wheel
Sun wheel
Satellite carrier
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Negative planetary gear, the standing gear ratio i0AC is negative
Three wheel planetary gear train
Willis equation:
When satellite carrier B is blocked
nB = 0
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Speed of individual wheels:
Planetary Gear
negative standing gear ratio i0AC
Directions of rotation of sun wheel A and ring wheel C are different,
when the satellite carrier B is blocked!
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Output coupled System
Fendt, Germany, developed a transmission system for agricultural tractors, which is in series production since 1996
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Power Split Drive
Input coupled System
Sundstrand Corporation - Responder transmission
New development by John Deere
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Best Efficiency ?
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Power Split Drive
System Example
Development by Claas