Piezo Valve Actuators
Dynamic Structures & Materials (DSM) works with companies to develop proportional valve products using piezo actuators. Interest has grown as product designers and managers learn how valves with proportional control capability can simplify and improve their systems, reduce cost, and improve system life.
DSM does not design valves, but has learned how to work closely with valve designers to create efficient and cost effective solutions to drive valves. Most applications require some actuator modification. However, as they are typically derivatives of our standard architectures, your project can be completed quickly with confidence in the outcome.
Our customer's confidential data is treated with extreme care. Much of what has been created over the years is proprietary and cannot be shown. A few examples are included below. Most of DSM's actuator architectures are compatible with valve driving conditions and can be considered for your valve applications.
Contact DSM today to speak to a sales representative or application engineer.
Possible Working Fluids
- Liquid hydrocarbon fuels: butane, propane, etc.
- Pressurized alcohol
- Cryogenic fluids: liquid nitrogen, liquid oxygen, liquid methane
- Compressed air
- CO2
- GN2
- High temperature propellant gases
Applications
- Fluid dispensing
- Liquid fuel dispensing
- Precision fluid metering
- Factory automation
- Proportional fluid control
- High speed dispensing
- High pressure dispensing
- Pilot valve actuation
Valve Actuator Capabilities
Maximum Line Pressure: up to 1500 psi (10.3 MPa)
Environmental Temperature: -320 °F to 392 °F (-196 °C to 200 °C)
Operating Frequency: up to 1000 Hz
Piezoelectric Actuators for Valve Applications
Valve applications requiring performance and package improvements may find advantage with piezoelectric-actuator-driven options. Use of piezoelectric actuators for valve applications has been available for many years. While some valve users may consider them a niche or specialty item, this review will present options and considerations that you might consider for your application.
Depending on application requirements, benefits may include:
- Low-power operation
- Zero power steady-state flow control
- Proportional control modes
- Optional switching or PWM control modes in the same system
- High dynamic servo response
- Fast open-loop response time
- Relative low heat generation for high cycle operation
- Vacuum and extreme environment operation capabilities
- High resolution precision control of flow
Low-Pressure Flow Control/Modulation with Piezoelectric Benders
Some servo-valve applications may consider the relatively low-cost piezoelectric bender elements. Bender actuators produce significant travel (>500 microns) with relatively low force. Flow modulation is achieved by the piezoelectric-bender driven seal. As shown in figures below from Festo [3], the piezoelectric ceramic bender looks like an electrically controlled bimetallic strip actuator. Principal advantages over a thermal or solenoid actuator is low-power operation, improved response, and finer proportionality. Because of the piezoelectric features, operation in highly magnetic environments is possible when properly designed. Contact DSM’s engineering services with your application requirements for a custom piezoelectric bender implementation.
In addition to pneumatics control, micro-fluid dispensing in inkjet printers has been a common application for piezoelectric bender actuator technology. See the Epson “Micro Piezo Technology” [4] for examples of ink dispensing actuators operating in a similar mode to piezoelectric bender actuators.
High-Pressure Flow Control Using Piezoelectric Stack Actuators
Piezoelectric stack elements extend piezo actuators into higher pressure servo-valve applications. Where piezoelectric benders can serve as pilot control elements (up to a few Newtons), actuators using piezo stack elements may control direct drive valve applications [1, 2]. A prominent application is the use of piezoelectric stack actuators (or piezo-actuators) in fuel injectors for superior flow and timing performance by rapidly pulsing the valve. Direct-drive applications are generally configured to use less than 100 micrometers of travel which is the amount found in many piezoelectric stack elements. Careful design of direct-drive valves allows piezoelectric stack actuators to operate at high frequency and precision control.
When valve actuation requires greater travel, DSM designers can consider mechanically amplified piezoelectric stack actuators. All of DSM’s Flextensional piezoelectric architectures may be suitable. The exact architecture is chosen depending on the application. The LPA and FPA provide from 50 to >2000 micrometers (microns) of valve poppet or pintle control [7]. Even mechanically amplified piezoelectric stack actuators can provide sub-millisecond pulse times when carefully implemented into a custom designed valve system.
The following photo shows an example of a Flextensional, amplified piezo actuator used in a valve. For the Small-scale Ballistic Cavitation (SBC) device produced by researchers at the University of Illinois, a piezo valve actuator from DSM allowed the researchers to build a benchtop high speed valve device [5].
Many various configurations and forms can be made for mechanical amplification of the piezoelectric stack actuator. Another configuration is shown below in the lever-arm actuator found in a published NASA JPL application [6].
DSM engineers welcome the opportunity to configure an actuator to your valve configuration or a derivative actuator device for specific applications.
References
- Anderson, Eric H., Lindler, Jason E., “Piezoelectric direct drive servovalve,” proceedings of SPIE 9th Annual International Symposium on Smart Structures and Materials, San Diego, California, U.S.A., March, 2002, Volume 4698-53.
- Hitchcox, Alan. “Piezo actuators: The future of servovalves?” Hydraulics & Pneumatics. https://www.hydraulicspneumatics.com/technologies/hydraulic-valves/article/21883964/piezo-actuators-the-future-of-servovalves (accessed April 1, 2020).
- Kunert, Thomas. “Valve with piezo technology”. Festo. https://www.festo.com/medlab/en/cms/10795.html (accessed April 1, 2020).
- “Micro Piezo Technology”. Epson. https://global.epson.com/innovation/core_technology/inkjet/micro_piezo.html (accessed April 1, 2020).
- Milner, M.P. and Hutchens, S.B. “A benchtop ballistic cavitation technique,” Extreme Mechanics Letters 28 (2019) 69-75.
- NASA Jet Propulsion Laboratory. “Piezoelectric Actuated Valve for Operation in Extreme Conditions”. Tech Briefs. https://www.techbriefs.com/component/content/article/tb/techbriefs/mechanics-and-machinery/20303 (accessed April 1, 2020).
- “Piezo Actuator Basics.” Dynamic Structures & Materials, LLC. https://www.dynamic-structures.com/actuators (accessed April 6, 2020).
Samples of DSM's Work
Fuel Dispensing Piezo Valve
The microvalve pictured above is a miniature piezo-based valve for dispensing liquid hydrocarbon fuel. DSM's micro dispensing valve was designed for a consumer product end-use and provides a low cost piezo actuated valve at high production volume. This valve dispenses fluid at a frequency up to 100 Hz with a line pressure up to 10 psi (68.9 kPa). The valve interfaces with adhesive-mounted inlet and outlet tube fittings and overall dimensions of 0.5 in. x 0.67 in. x 0.28 in. (12.5 mm x 17 mm x 7 mm).
High Temperature Propellant Gas Valves
Sub-Millisecond Piezo Valve Actuator Used for Benchtop Ballistic Device
DSM provided an actuator to open and close a dispensing valve in less than 5 milliseconds. DSM's actuator provided the sub-millisecond pulse time and 4350 psi (30 MPa) pressure operation necessary for the Small-scale Ballistic Cavitation (SBC) device.
Researchers at the University of Illinois at Urbana-Champaign built an SBC device that models ballistic damage in soft materials without the disadvantages of traditional ballistic testing experiments. The researchers chose DSM's valve actuator because solenoid actuated devices did not have the necessary high frequency and operating pressure capabilities.
A Small-scale Ballistic Cavitation (SBC) technique is available from researchers at the University of Illinois at Urbana-Champaign. A piezo actuator that would open and close in less than 5 milliseconds was required to operate the SBC. The high-speed valve dispenses pulses of air from a high-pressure chamber (up to 30 MPa or 4,300 psi) into a soft material sample. A schematic of the device is shown above.
The air pulses form cavities inside the sample that replicate the effects of ballistic damage. The figure below shows the cavities formed in the soft material sample from two different pressure levels at 0, 2 and 7 milliseconds.
Researchers determined that a high-frequency piezo actuator was required to operate the valve. Solenoid actuated devices did not have the combination of sub-millisecond open/close times and ability to operate at pressure levels up to 30 MPa (Milner and Hutchens 72). The researchers at UIL Urbana-Champaign asked Dynamic Structures and Materials for an actuator to drive the benchtop testing drive. DSM coordinated with the researchers to design a custom solution. The high frequency piezo actuator, is shown in the figure below.
The sub-millisecond pulse time supplied by DSM’s piezo actuator allowed the researchers to build a device that modeled ballistic damage without the disadvantages of traditional ballistic testing experiments.
DSM’s high frequency piezo actuator (PSA) product pages have datasheets for actuators similar to the one used in this testing device. DSM has recommended applications listed on the PSA pages and can customize this actuator architecture for new applications.
For more information on the benchtop ballistic cavitation technique, check out the Extreme Mechanics Letters journal referenced below.
Reference
Milner, M. P. and Hutchens, S. B. “A benchtop ballistic cavitation technique,” Extreme Mechanics Letters 28 (2019) 69-75.
Cryogenic Isolation Valve Actuator
Using patented Flexframe Piezo Actuator technology, DSM designed and built a system that modulated flow in a smooth, voltage-controlled manner. The piezo valve actuator had minimal temperature sensitivity as Flexframe technology eliminates the need for bearings, bushings, or lubrication. This eliminates the possibility of binding as a result of thermal contraction/expansion discrepancies. The piezo valve actuator measured approximately 2.2 in. x 0.77 in. x 0.59 in. (56 mm x 20 mm x 15 mm), weighed less than 3 ounces (75 grams), and had over 0.012 in. (300 microns) of travel. Learn more about DSM's cryogenic and harsh environment capabilities on the Extreme Environment Devices page.
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