Prepared by: Yiding Han Dept. of Electrical and Computer Engineering Utah State University

1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Hydraulic actuators Prepared by: Yiding Han Dept. of Electrical and Computer Engineering Utah State University E: yiding.h@aggiemail.usu.edu 3/7/2008

2. Outline • Reference list • To explore further • Advantages of hydraulic systems • Major applications • Patent • Basic working principle • Working illustration • Components of hydraulic system • Position Control • Major specifications • Limitations • Costs & where to buy • Interesting applications ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

3. Reference list • http://home.wxs.nl/~brink494/frm_e.htm • http://hyperphysics.phy-astr.gsu.edu/Hbase/pasc.html • http://en.wikipedia.org/wiki/Hydraulic_system • http://science.howstuffworks.com/hydraulic1.htm • Mechatronics Handbook ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

4. To Explore Further • tutorial and technical support of Hydraulic systems http://science.howstuffworks.com/hydraulic.htm http://en.wikipedia.org/wiki/Hydraulic_system http://home.wxs.nl/~brink494/frm_e.htm http://www.hydraulicsupermarket.com/technical.html • suppliers of Hydraulic systems and parts http://www.globalsources.com/manufacturers/Hydraulic.html http://www.hydparts.com/ ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

5. Advantages of hydraulic systems • High Torque and Force • Less total horsepower and flow needed • Relatively light in weight • Simple and extremely reliable • Relatively quiet in operation • Easy to control ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

6. Major applications http://news.thomasnet.com/images/large/007/7599.jpg • Construction Hydraulics • Industry Hydraulics • Forestry Hydraulics • Agricultural Hydraulics • Mining Hydraulics • Marine Hydraulics • Oil & Gas Hydraulics http://www.seawayheavylifting.nl/images/marine-transportation10.jpg ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

7. Patent • Title: Hydraulic cylinder actuator • Document Type and Number: United States Patent US3234853 • Author: Aber, Joseph S. • Publication Date: 02/15/1966 • URL: http://www.freepatentsonline.com/3234853.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

8. Basic working principle • Hydraulic systems operate according to Pascal's Principle - Pressure is transmitted undiminished in an enclosed static fluid. • The figure on the right side illustrates how force multiplication can be achieved by the applying pressure according to Pascal's principle, which for the two pistons implies P1 = P2 • Therefore, with the automatic hydraulic lift, heavy load can be lifted with a small force. Of course, assuming in an ideal case with no frictional loss, work cannot be multiplied: Winput = Woutput http://hyperphysics.phy-astr.gsu.edu/Hbase/fluids/imgflu/hpress.gif ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

9. Working illustration Below is an animation that illustrates how hydraulic cylinder actuator system functions. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

10. Hydraulic pumps • A Hydraulic pump is a pump that is used in hydraulic drive systems. • Hydraulic pumps can be hydrostatic or hydrodynamic. • Hydrostatic pumps are positive displacement pumps. • Hydrostatic pumps can be fixed displacement pumps, in which the displacement cannot be adjusted, or variable displacement pumps, which have a more complicated construction that allows the displacement to be adjusted. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

11. Types of Hydraulic pumps • (1) Gear pumps Simple, reliable and economical. But the efficiency is not very good. Provide low to mid pressures from 140 to 180 bar. • (2) Gerotor pumps Improved gear pumps, optimized to provide mid pressures. • (3) Rotary vane pumps Higher efficiencies than gear pumps, but are also used for mid pressures up to 190 bars in general. (1) (2) (3) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

12. Types of Hydraulic pumps cont… • Axis pumps have the best efficiency of all pumps. with a working pressure above aprox. 250 bar. • Bent axis pumps • Axial piston pumps swashplate principle • Other hydraulic pumps • Radial piston pumps (for high pressure and relatively small flows) • Peristaltic pumps (generally used for low pressure and aggressive fluid/chemical) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

13. Hydraulic cylinder • Hydraulic cylinders (also called linear hydraulic motors) are mechanical actuators that are used to give a linear force through a linear stroke. • The pushing or pulling force of a hydraulic cylinder is: ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

14. Components of hydraulic cylinder • Cylinder barrel The cylinder barrel is mostly a seamless thick walled forged pipe that must be machined internally. The cylinder barrel is ground and/or honed internally. • Cylinder bottom In most hydraulic cylinders, the barrel and the bottom are welded together. This can damage the inside of the barrel. Therefore it is better to have a screwed or flanged connection. In that case also the barrel pipe can be maintained and/or repaired in future. • Cylinder head The cylinder head is sometimes connected to the barrel with a sort of a simple lock (for simple cylinders). In general however the connection is screwed or flanged. Flange connections are the best, but also the most expensive. A flange has to be welded to the pipe before machining. The advantage is that the connection is bolted and always simple to remove. For larger cylinder sizes, the disconnection of a screw with a diameter of 300 to 600 mm is a big problem as well as the alignment during mounting. • Piston • Cylinder bottom connection • Piston rod connection • Other ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

15. Special hydraulic cylinders • Telescopic cylinder • telescopic cylinders can be two, three, four, five and even six stroke. In general telescopic cylinders are much more expensive that normal cylinders. Most telescopic cylinders are single acting (push). Double acting telescopic cylinders must be specially designed and manufactured. • Plunger cylinder • A hydraulic cylinder without a piston or with a piston without seals is called a plunger cylinder. A plunger cylinder can only be used as a pushing cylinder; the maximum force is pistonrod area multiplied by pressure. This means that a piston cylinder in general has a relatively thick pistonrod. • Differential cylinder • A differential cylinder acts like a normal cylinder when pulling. If the cylinder however has to push, the oil from the pistonrod side of the cylinder is not returned to the reservoir, but goes to the bottomside of the cylinder. In such a way, the cylinder goes much faster, but the maximum force the cylinder can give is like a plunger cylinder. A differential cylinder can be manufactured like a normal cylinder, and only a special control is added. Telescopic cylinder ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

16. Position Control A typical model of Hydraulic Servo system for position control ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

17. Major Specifications • In general, hydraulic actuators are commonly specified by: • Linear/rotary • Fluid type • Piston rod diameter • Bore diameter • Maximum Operating Pressure • Operating Temperature • Force bandwidth • Mounting style • Stroke ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

18. Limitations • Unsuitable for high speed applications • Difficult to reduce in size • Unsuitable for specific position control that requires high precision • Cylinder stroke length has certain limits • Fluid type requirements, cannot use pressurized fluids • Fluid leaking may result in significant performance drop down ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

19. Cost • Small scale/Low-end application: $100 - $10000 • Large scale/High-end application: More than $10000 • Specific projects: Huge cost, depending on the application. The hydraulic powered jacking and leveling Crawler transport in NASA costs $7 million each (about $14 for both crawlers) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

20. Where to buy Hydraulic systems for commercial applications • http://www.precisionfluidpower.com/ • http://search.globalspec.com • http://www.hydparts.com/ Hydraulic systems for industry grade applications • Unavailable at retail stores or online purchase. Projects require contracts with specific vendors. • http://www.buffalohydraulic.com/index.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

21. Interesting Applications • Diesel powered, hydrostatic drive motorcycle: http://www.hydraulicinnovations.com/index.htm • NASA World record lifting/weighing project: http://www.buffalohydraulic.com/projects.html?pjid=1 • Hydraulic Hybrids vehicles: http://www.nextenergy.org/industryservices/Hybrid__Hydraulics.asp ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators