Design Closed Circuit Blue Graphics Concept SauerDanfoss Introduction
Design Closed Circuit © Blue Graphics Concept Sauer-Danfoss Introduction, May 2012
MENU Main Menu System Overview Filtration Functionality of components Reservoir Basic Hydrostatic (closed circuit) 2 Hydraulic Fluids Heat Exchanger
MENU Main Menu System Overview Filtration Functionality of components Reservoir Basic Hydrostatic (closed circuit) 3 Hydraulic Fluids Heat Exchanger
MENU 1. System Overview Hydrostatic Transmission • Continuously variable speed w/o loss of traction Tr active Force [N] hydrostatic transmission Installed Engine Power - source 1 - Motor Ratio Pump Ratio A Speed [km/h] B 4
MENU 1. System Overview Hydrostatic Transmission • Motor output torque and speed depends on pump and motor displacement • Speed of hydrostatic transmission is reciprocal to displacements • Torque is proportional to displacements 5
MENU Main Menu System Overview Filtration Functionality of components Reservoir Basic Hydrostatic (closed circuit) 6 Hydraulic Fluids Heat Exchanger
2. Functionality of Components Integrated Charge Pump 7 MENU
2. Functionality of Components Integrated Charge Pump • Charge pump is a fixed displacement pump (gerotor-type) which is directly connected to the pump input shaft • Charge pump displacement should be sized to approximately 10% of whole system displacement (pump and motor(s) displacements) in most applications 8 MENU
2. Functionality of Components Charge Pump - Functions Charge Pump flow rate functions: • Replenish leakage oil of pump and motor • Replenish loop flushing oil through the flushing valve • Provide flow for the servo control systems • Provide flow for auxiliary circuit functions e. g. parking brake release Charge Pump pressure functions: • Maintain low loop pressure • Provide sufficient pressure to activate the servo control systems 9 MENU
2. Functionality of Components Charge Pressure Relief Valve 10 MENU
2. Functionality of Components Charge Pressure Relief Valve • Charge pressure relief valve is necessary to maintain low loop pressure • Protects the charge pump by limiting the charge pressure • Excess charge pump output flow is directed into the pump case 11 MENU
2. Functionality of Components Charge Check Valve 12 MENU
2. Functionality of Components Charge Check Valve • It protects the charge pressure system (charge pump), otherwise a backflow from high pressure side will damaged the charge pump 13 MENU
2. Functionality of Components Loop Flushing System 14 MENU
2. Functionality of Components Loop Flushing System • Loop Flushing is necessary because of cooling requirements and contamination removal of system circuit • The LF-system removes fluid from the low pressure side of the closed circuit system • Loop Flushing valves are available with different flow rates to optimize flush flow requirements in all system operating conditions 15 MENU
2. Functionality of Components High Pressure Relief Valve (HPRV) 16 MENU
2. Functionality of Components High Pressure Relief Valve (HPRV) • High pressure relief valves are needed in hydrostatic transmission systems to limit maximum pressures – Pressures above the product ratings will damage the transmission – HPRV protect pumps, motors, hoses and other system components 17 MENU
2. Functionality of Components Pressure Limiter • Pressure Limiter is a non dissipative high pressure control • Limits the heat generated in the system when pressures are too high • PL changes the displacement of the pump in response to high system pressure 18 MENU
2. Functionality of Components Bypass • Bypass function allows an internal connection to be made between the two loops in the hydrostatic transmission • Function allows the vehicle to be moved without the engine running – Allows for disabled vehicles to be loaded onto a trailer or moved off the road – Intended to be for slow, short durations otherwise the hydrostatic transmission can be damaged 19 MENU
MENU Main Menu System Overview Filtration Functionality of components Reservoir Basic Hydrostatic (closed circuit) 20 Hydraulic Fluids Heat Exchanger
MENU 3. Hydraulic Fluids What do you know about Hydraulic Fluids? Sun Water Dirt Air Blood Alcohol 21
MENU 3. Hydraulic Fluids Overview Hydraulic Fluid Groups 1. Mineral oil based hydraulic fluids 2. Biogradeable hydraulic fluids • Syntetic ester (HEES) • Rape oil alkaline (HETG) 3. Fire resistance fluids • ATEX Regulation 22
MENU 3. Hydraulic Fluids Recommended Hydraulic Fluids • Find recommended Hydraulic Fluids for Sauer-Danfoss hydrostatic components in Technical Literature* • Fluids meeting the technical literature requirements will very likely provide acceptable unit life • field testing is the only truly indication of fluid performance • Sauer-Danfoss warranty claim policies do not apply for fluid related damage *: “Hydraulic Fluids and Lubricants Technical Information”; page 20 23
MENU 3. Hydraulic Fluids Physical Behavior 1. Viscosity • • • Viscosity grade (VG) Depends on temperature and pressure Compromise between flow losses and leakage 2. Density • Depends on temperature and pressure 24
MENU 3. Hydraulic Fluids Physical Behavior Temperature-Behavior kinematic Viscosity Pressure-Behaviour Temperature 25
MENU 3. Hydraulic Fluids Viskosity and Temerature Limits • Viscosity and temperature limits in the table “Viscosity and temperature limits” in technical information* are to be observed • Under normal operating condition it is recommended to keep the temperature in the range of 30 °C to 60 °C • Rule of thumb: fluid temperature increase from 80 °C [176 °F] to 90 °C [194 °F] may reduce fluid life by 50 % *: “Hydraulic Fluids and Lubricants Technical Information”; page 19 26
MENU 3. Hydraulic Fluids Additives Improvement of oil attributes • Viscosity-temperature behavior • Wear protection • Corrosion protection • Ageing resistance • Foam prevention • Bond to dirt particles 27
MENU 3. Hydraulic Fluids Selection Criteria • Manufacturer‘s instructions • Release of diverse oils • Depends on system • • Application (vehicle, temperature conditions) Fill rate • Application environment • • Climate Area of application (i. e. environmental, flammability regulations, etc. ) 28
MENU 3. Hydraulic Fluids Additional Information • Technical Information “Hydraulic Fluids and Lubricants” (520 L 0463) • Technical Information “Experience with Biodegradable Hydraulic Fluids” (520 L 0465) 29
MENU Main Menu System Overview Filtration Functionality of components Reservoir Basic Hydrostatic (closed circuit) 30 Hydraulic Fluids Heat Exchanger
MENU 4. Filtration Contamination Sources of contamination: – – Installation System components Fill oil Repair of a unit Types of contamination: – – – Metal Synthetic materials Organic materials Plastic Water Etc. Scratches on Piston Shoe 31
MENU 4. Filtration Cleanliness Classes ISO 4406 1999: number of particles cleanliness classes 1/ml (ISO 4406) • Specification of three cleanliness classes correlated to particle size ≥ 4; ≥ 6; ≥ 14 [μm] • Example: ISO 18/16/13 32 0, 01 -0, 02 1 0, 02 -0, 04 2 0, 04 -0, 08 3 0, 08 -0, 16 4 0, 16 -0, 32 5 0, 32 -0, 64 6 etc. 40 -80 13 80 -160 14 160 -320 15 320 -640 16 640 -1300 17 1300 -2500 18 2500 -5000 19 5000 -10000 20 10000 -20000 21 20000 -40000 22 40000 -80000 23 80000 -160000 24
MENU 4. Filtration Cleanliness Classes Sauer-Danfoss recommends the cleanliness classes below for different applications* Product Steering components with open center Orbital motors Steering components with LS and closed center Proportional spool valves Axial + radial piston pumps and motors Gear pumps and motors Cartridge and electrohydraulic valves Required cleenliness class ISO 4406 -1999 22/20/17 22/20/16 21/19/16 22/18/13 18/16/13 Maximum class at machine start up 25/22/17 *: “Design Guideline for Hydraulic Fluid Cleanliness Technical Information” (520 L 0467), p. 13, Spreadsheet: “Fluid cleanliness 33 requirements according to product“
MENU 4. Filtration Kind of Filtration Partial flow filtration + necessary) Small filter Partial backflow of oil w/o filtration Charge pump unprotected (pre-filtration 34
MENU 4. Filtration Kind of Filtration Full flow filtration + + - Complete oil filtration Small filter Charge pump unprotected ( pre-filtration necessary) 35
MENU 4. Filtration Kind of Filtration Suction filtration + - Charge pump protected Large filter surface necessary Disadvantageous at low temperature 36
MENU Main Menu System Overview Filtration Functionality of components Reservoir Basic Hydrostatic (closed circuit) 37 Hydraulic Fluids Heat Exchanger
MENU 5. Reservoir Overview Art der Filterung Tasks: • Fluid reservoir • Ensures there is enough oil for hydraulic system • Cooling • Separates dirt, water and air • Assures smooth fluid flow (laminar flow) at suction 38
MENU Main Menu System Overview Filtration Functionality of components Reservoir Basic Hydrostatic (closed circuit) 39 Hydraulic Fluids Heat Exchanger
MENU 6. Heat Exchanger Function and Type Removal of hydraulic-system heat • Prevents overheating of oil • Ideal oil-temperature should be 60 to 80°C Construction type in mobile hydraulic • Oil-air-heat exchanger Oil-air heat exchanger 40
MENU 6. Heat Exchanger Design Criteria vehicle engine cooler 41 fan SD FD system
MENU 6. Heat Exchanger Sauer-Danfoss Fan Drive example: closed circuit 42
MENU The End 43
Many Thanks for YOUR Attention! When Chuck Norris says “ 420 bar" he is not quoting the pressure rating of the H 1 B motor, he is telling you how much pressure his foot will apply to your face. The three things that make hydraulics work: 1. Flow 2. Pressure 3. Chuck Norris 44 MENU
Overview Literature Sources - Source 1 - Ölhydraulik – Handbuch für die hydrostatisch Leistungsübertragung in der Fluidtechnik; Findeisen, D. ; Springer 45 MENU
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