Marquette University Milwaukee School of Engineering Purdue University University of California, Merced University of Illinois, Urbana-Champaign University of Minnesota Vanderbilt University Hybrid MEMS Proportional Pneumatic Valve Project 16HS1 Presenter: Nathan Hagstrom, Graduate Research Assistant Principal Investigator: Thomas Chase University of Minnesota CCEFP Industry University Summit April 5, 2017
Overview What does this valve hope to accomplish? What current miniature valves are commonly used? What is a hybrid MEMS valve? How well does it work? First experimental results What is the future for the project? Prototype hybrid MEMS valve parts 2
Project Summary Use MEMS fabrication techniques to micromachine an orifice array Use Piezoelectric stack actuator to modulate flow Leverage these two technologies to create an ultra efficient pneumatic proportional valve Courtesy University of Illinois Project TB6 Team Benefits: Near zero power to hold at a fixed deflection Near zero heat generation Low cost Silent operation 3
Current Miniature Valve Competing Strategies Motion Amplified Piezoelectric Stack Valve [1] : Large displacement stroke Large mass flow rates High operating pressures Piezoelectric Bender Valve [2] : Large operating bandwidth Low power consumption [1] http://www.dynamic-structures.com/actuators#fpa [2] https://www.festo.com/cms/nl-be_be/22394.htm 4
Hybrid MEMS Valve Concept (1 of 2) area = 0.25 p D 2 area = p D d Full flow when d 0.25 D 5
Hybrid MEMS Valve Concept (2 of 2) Orifice Array Single Orifice Orifice Diameter: 160 um Actuator Displacement: 40 um Flow Area: 1.287 mm 2 Orifice Diameter: 1.28 mm Actuator Displacement: 320 um Flow Area: 1.287 mm 2 6
Basic Hybrid MEMS Valve Architecture Exploded View: Assembled View: Seal Plate Carrier Seal Plate Orifice Plate Piezostack Actuator Piezostack Boss Piezostack Actuator Seal Plate Carrier Seal Plate Orifice Plate Valve Enclosure 7
Assembled Hybrid MEMS Valve Actuator Leads Actuator O-Ring Valve Enclosure 8
Hybrid MEMS Valve Strategies Electromagnetic Valve Piezostack Valve with Motion Amplifier Piezoelectric Bender Valve Hybrid MEMS Valve Operating Pressures 0 0 - + Flow Rate 0 + - 0 Power Consumption Response Time Flow Proportionality 0 + + + 0 0 0 + 0 + - + 9
Why Fabricate Orifice Array using MEMS Fabrication Techniques? Small orifice size in array format allow for use of piezostack actuator Cost effective bulk micromachining of silicon Silicon is stiffer and lighter than traditional materials 10
Why Utilize of Piezostack Actuation? Thorlabs PK2FVP2 L = 40 mm d max = 45 mm F max = 1000 N Low static valve power consumption Fast response speed Proportional flow control at high operating pressures Quiet operation Small temperature rise at low operating frequencies Can be used in a magnetic field Compact 11
MEMS Orifice Plate Flow Performance 64 X 160mm orifices 12
MEMS Orifice Plate Flow Performance 64 X 160mm orifices 13
Piezoelectric Actuation Performance Repeatable Non-linear Hysteretic Capacitive Displacement Sensor Piezostack Actuator 14
Piezoelectric Actuation Performance Repeatable Non-linear Hysteretic Capacitive Displacement Sensor Piezostack Actuator 15
Hybrid MEMS Valve On Off Performance Flow over a 6/5 bar pressure gradient: 55 SLPM 16
Hybrid MEMS Valve On Off Performance Flow over a 6/5 bar pressure gradient: 55 SLPM 17
Hybrid MEMS Valve Turndown Ratio 18
Hybrid MEMS Valve Turndown Ratio 19
Hybrid MEMS Valve Proportional Flow Performance Highly Repeatable proportional flow control Hysteresis characterized by open loop voltage input 20
Hybrid MEMS Valve Proportional Flow Performance Highly Repeatable proportional flow control Hysteresis characterized by open loop voltage input 21
Hybrid MEMS Proportional Valves Goal: Create ultra-efficient miniature proportional pneumatic valves Alignment with CCEFP Strategy: Compactness, Efficiency Test Bed: Ankle-Foot Orthosis (TB6) Original contribution: Piezostack valve with no need for motion amplifier Competition: Piezobender valves, piezostack valves using motion amplifier Major Objectives/Deliverables Exploit piezoelectric materials in pneumatic valves Lowest power consumption on market Fastest response time on market Proportional control over large range of pressures Potentially revolutionize pneumatic valve technology Progress Utility patent filed Orifice arrays fabricated Prototype valve assembled Initial experimental results obtained Next Steps Measure dynamic performance attributes (May 17) Quantify contamination resistance (June 17) Demonstrate pneumatic alpha prototype on Ankle-Foot Orthosis (Feb 18) Seek Funding beyond 2018 Hydraulic pilot valve (May 18) Develop position feedback capability (Aug 18) 22
Summary of Valve Benefits Near zero power to hold at a fixed deflection Near zero heat generation Low cost Silent operation Proportional Control Non magnetic 23
Conclusion Successful operation of first prototype Proportional but non-linear flow control Will be fixed with feedback control system High operating flow rates and pressures 10:1 turndown ratio achieved across all operating pressures, will be further improved The efficiency, compactness and performance of hybrid MEMS valves hold the potential to revolutionize pneumatic valve technology 24
Acknowledgements Previous Graduate Students: Alex Hargus Industry Champions: Enfield Technologies Parker Hannifin Corporation Festo Bimba 25
Questions? 26