Assignment#01: Literature Survey on Sensors and Actuators ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Hydraulic Cylinders Prepared by: Cordel Johns Dept. of Electrical and Computer Engineering Utah State University T: (435)797-; F: (435) (ECE Dept.) 3/10/2006

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-2 Outline –Reference list –To probe further –Major applications –Basic working principles –Major specifications –Selecting a cylinder

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-3 Reference list Jeff Loosli, Manager, Intermountain Hydraulics

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-4 To explore further (survival pointers of web references etc) –This is the sight for Parker's Hydraulic Cylinder division. One of the major suppliers of all things hydraulic, it is an excellent place to start. Reading through their catalog, and creating a part number as they explain it will walk you through what you need. Most have good explanations of what each parameter is. They do tend to brag about their cylinders, but as a starting point, it is excellent

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-5 Major applications Excavation machinery Industrial production Automobiles/ Transportation Farming equipment Presses Flight simulators

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-6 Basic Layout of a cylinder

Basic Principles of a Cylinder Pressurized oil is channeled into a cylinder The oil pushes on the piston, forcing it one direction or the other The piston, in turn pushes the piston rod in the same direction. This is how pressure is turned into work.

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-8 Specifications Bore - diameter of piston rod Stroke - distance the piston rod extends. –Measured by subtracting length of rod retracted from the length of the rod extended Pressure- both input and output Side load- any forces not parallel to the piston rod Mounting- how cylinder is held in place and interacts with environment Ports- locations for attaching hoses Cushioning

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-9 Side load A side load is any non-parallel force on the piston rod. This is especially relevant in horizontally mounted cylinders, especially those of great length. For cylinders with a side load, a stop tube is often used. This increases the space between the piston and the end of the cylinder, providing a more stable support for the rod Most manufacturers that provide stop tubes also provide a table, or directions, to help select it’s length.

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-10 Stop Tube

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-11 Mountings Mountings are fairly self explanatory. They allow a cylinder to be fastened to whatever it is moving. Mountings can effect the load the cylinder can bear They are selected on what motion you require from the cylinder

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-12 Examples of Mounts

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-13 A few more Mounts

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-14 Motion of cylinders Different applications require different cylinder mounts. i.e. Dump truck beds require that the cylinder move with the bed, whereas a sluice gate in a dam requires only an up or down motion. (you can see how some of the mounts could affect this) Some applications require that the cylinder pull as well as push. This affects the necessary size of the cylinder. (We will expound on this later) Select your mount based on the required motion. Be aware that some mounts may not be available in a high enough strength rating

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-15 Ports For non-metric cylinders, there are two main styles. –SAE-ORB (straight thread, O-ring) ports have an O- ring that seals between the fitting and the port. Of the two port types, this one gives you a better seal, though the O-ring can cause issues(such as hardening with age) –NPT Tapered pipe thread seal on the threads. Sealants such as Teflon tape are often used in conjunction with this type of fitting

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-16 Port drawings These are adapters, for the purpose of showing what both the male and female portions of the previously mentioned port types look like

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-17 Cushions Cushions slow the movement of the piston rod as it nears the ends of it's stroke They can be placed at either or both ends of the cylinder The cushion blocks the normal hydraulic fluid flow, forcing it to travel through an adjustable needle valve. This route controls the speed of the fluid, and therefor the speed of the rod.

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-18 I/0 pressure of a cylinder, Part 1 For example, if you have a 5” cylinder(5” diameter), and an input pressure of 10 psi, You will have an output pressure of lbs. of force pushing the rod out.

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-19 I/O pressure of a cylinder, Part 2 The amount of force applied to retract the shaft is calculated in the same way as the force to push the shaft out, except that the diameter of the shaft reduces the surface area of the piston. The side of the piston that the extrudes from is called the annulus. The area of the annulus is the Piston Area minus the Rod Area. Obviously, if you require the same or greater force to retract the piston, you will need a bigger cylinder than if you required the same force to push the load out

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-20 Cylinder Speed The speed of a cylinder is dependent on the volume of the cylinder, and the volume of hydraulic fluid the rest of the system can output The volume of a cylinder is the area of the piston * the length of the stroke There are 231 cubic inches/gallon The same 5” cylinder from the previous slide, having a 5” stroke, with an input of 5 Gal/min will move ~82 in/min

03/02/06 ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators Slide-21 How to select a cylinder What do you need to move? –Bore size, Rod size, and cylinder ratings How much pressure do you require to move the load How far do you need to move it? –Stroke This corresponds to the stroke of the cylinder

How to select a cylinder How fast do you need it to move? –Input Gallons Per Minute of cylinder & cylinder volume If you are designing a new system, you can decide on a cylinder that best meets your other needs, and design a system that can supply the GPM it requires When replacing a cylinder, you have to find a cylinder that fits the system you already have(pressure and GPM that the system supplies

How to select a cylinder Which direction\s do you need to move it? –Mountings Do you need it mobile or immobile? Do you need it to mount parallel to a surface, or perpendicular? Do you need it to move with the load? –Side loading & Rod size Do you need a stop tube, or supports for the load, to prevent or support side loading? Side loading also figures into rod size, so as to prevent bending of the rod

How to select a cylinder Ports –Depending on the manufacturer, you may have a choice on ports. Some may cost more. Select a fitting style. This is primarily based on preference, but double check the pressure ratings to ensure meeting your needs.

How to select a cylinder Cushions –Are sudden stops and starts going to injure your load? –Are you operating at high enough speeds that the shock will damage the cylinder? Cushions of various lengths are available, depending on the amount of shock at each end of the stroke. The ride below has a 10” cushion as a hardware safety factor for the occupants