Unlike most pneumatic positioning systems on the market, which control the position of the actuator with directional flow, AVENTICS utilizes our expertise in direct acting proportional pressure regulators. This principle of operation can be applied equally well in both piston rod and rodless pneumatic cylinders in a considerable range of bore sizes and strokes.
The AVENTICS EPPS (Electro-Pneumatic Positioning System) is a new technology and offers advantages over the previous methods of pneumatics positioning. The traditional pneumatic way of doing this type of positioning is through flow control. Virtually all pneumatics systems have some small pressure loss (possible leaks, etc.). When the flow control valve is in its closed center state to hold a position, once there is any kind of pressure loss on one side or the other, it starts moving back and forth slightly hunting for the true position, a condition called “dithering” or “drifting”. The EPPS with proportional control uses constant pressure equalized on both sides of the actuator piston, which eliminates the dithering, allowing a smoother application. Positioning accuracy is typically +/- 1mm.
The EPPS typically offers better delivery than traditional pneumatic systems that require the piston rod to be gundrilled. With the EPPS, many standard cylinders (including rodless) can be used because it uses an externally mounted sensor – eliminating the need for gundrilling. The EPPS typically offers cost advantages over traditional pneumatics positioning and electro-mechanical positioning systems. A 100% duty cycle means no worries about cycle rate and overheating.
The EPPS system uses a special position controller requiring no programming and 12 bit resolution. Analog command and feedback is 0-10Vdc or 4-20mA. The controller offers easy set-up and is field adjustable. A single part number for the controller covers all configurations.
Standard AVENTICS direct acting proportional pressure regulators (E/Ps) act as an interface between the controller and the actuator. This provides constant pressure regulation to eliminate the traditional dithering or drifting. The E/Ps offer a range of flow from 5 scfm to 92 scfm. Analog command and feedback is 0-10Vdc or 4-20mA, with resolution of 10 bit. The AVENTICS ED02 compact E/P is most often used.
The SM6 series of sensors are used with the EPPS. The SM6 can be used in cylinders with a 6mm t-slot with strokes up to 256mm. The SM6-AL version can be used for cylinders up to 1007mm stroke. The sensors have repetitive precision of 0.06% full scale, and have a user teachable measurement range.
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