1E: On-off Valve Based Control
[Please include designated project number]
1. Executive summary:
Research Team
Project Leader:
Other Faculty:
Post Doc(s):
Graduate Students:
Undergraduate
Students:
Industrial Partner(s):
John Lumkes, Agricultural and Biological Engineering, Purdue Univ.
Monika Ivantysynova, Mechanical Engineering, Purdue Univ.
Perry Li, Mechanical Engineering, Univ. of Minnesota
Steve Frankel, Mechanical Engineering, Purdue Univ.
None
Mark Batdorff, Ph.D. student
To be recruited
Parker-Hannifin
Statement of Project Goals
The goal of the project is to develop advanced models and theoretical understanding of high
speed digital hydraulic valves operating at higher pressures.
Project Role in Support of Strategic Plan
The project will develop compact and efficient hydraulic systems utilizing high speed valves
capable of rapidly and precisely controlling hydraulic power in a throttle-less manner. An
understanding of the interaction between the electrical, mechanical, and hydraulic systems will
enable accurate models to be developed and later combined with larger system models for the
optimization of system efficiency, operating pressure, reliability, dynamic response, and noise
reduction. Successful completion of this project will have a significant impact on the ability to
develop and implement the control algorithms proposed in project 1.A, the ability to implement
to the concepts described in project 1.E, and the feasibility of project 2.B. The work done in
project 3.C will enhance the results of this project by enabling more accurate CFD simulation of
the valves. This project will support the efficiency thrust and the compactness thrust of the
strategic plan. The efficiency thrust is supported through the reduction of metering losses in
typical fluid power systems while the compactness thrust is supported through the development
of high speed positive sealing digital valves capable of operating at higher than standard
pressures.
Overall Project Scope Summary
This project will focus on the design and simulation of high speed digital valves and several
applications. Pertaining to the valve itself, high pressure operations, unsteady flow dynamics,
and transient electromagnetic dynamics will be modeled and the results used to develop
electronic control algorithms to accurately and efficiently control and actuate the valve. Within
the scope of this phase is building a prototype to experimentally validate the flow, leakage, and
electromagnetic models. While out of scope for this phase, future system integration and
applications complement the efforts of projects 1.A, 1.E, 2.E, and 3.C. and may be considered in
follow-up projects.
2. Project Description
A. Description and explanation of research approach
In recent years Purdue has designed and prototyped a high speed digital valve that can be
configured to be pressure balanced with positive contacting sealing surfaces. This effort provides
a necessary starting point for enabling the successful development of new high pressure pump
and control components. Understanding the fluid dynamics, electromagnetic transients, leakage
flows, and mechanical deformations will allow the development of high pressure virtually
variable pumps, motors, and valves where the efficiency is maintained at high pressures by
controlling the leakage and compressibility losses. This work is an important and complementary
component to the other ongoing work in the center. Large improvements in both the compactness
and efficiency thrusts will be realized as the fluid properties are engineered for the higher
pressures and components are developed to better utilize and implement the results.
As system pressure is increased, efficiency tends to be decreased due to increased leakage and
compressibility losses. It becomes increasingly difficult to seal using sliding surfaces (i.e. spool
overlap and kidney/valve plates) and positive contact sealing surfaces are preferred at higher
pressures to minimize leakage losses. In addition, the goal of on/off valve control at these higher
pressures further complicates the research. One example application, high pressure pumps,
usually rely on check valves in place of kidney valve plates and in doing so become fixed
displacement unidirectional machines. High pressure, high speed on/off valves can enable a high
pressure pump/motor to become variable displacement and bidirectional if the actively controlled
valves replace the check valves. This has benefits in the compactness thrust and urban vehicle
test bed since high pressure hydrostatic transmissions become possible. The be able to design
these machines in later phases a better understanding of the fundamental aspects of the fluid
dynamics, electromagnetic characteristics, and sealing contact surfaces is necessary.
There are four basic areas where fundamental science must be applied in this project. Current
research indicates that state-of-the-art CFD code utilizing dynamic meshing is not very accurate
above switching dynamics of 1000Hz. The proposed on/off valves will cycle significantly faster
than this rate. The transient flow forces and resulting cavitation or surface erosion are not well
understood in these ranges. Electromagnetic transients constitute a similar problem. High
frequency electromagnetic effects such as eddy currents affect the transient force of the actuator.
Although eddy currents are relatively well understood in AC transformers there is still much
work to do for electromagnets. Effects of eddy currents can be reduced with driving circuitry
such as peak & hold or possibly momentary reversed currents and through the minimization of
magnetic diffusion time constants. The third area includes the mechanical dynamics, impact
forces, and contact sealing models. The combination of high pressures coupled with high
switching speeds has the potential to negatively affect the reliability and lifespan of high speed
valves. Finally, the behavior of the fluid is also important at the higher pressures and high
switching speeds. This aspect of the project will be supported by the work at partner institutions
and is necessary to complete the system model of switching valves.
To adequately address, study, and find solutions to these issues a simulation model and the
underlying theoretical models must be developed. The “novel” features, i.e. improvements,
additions, and changes to the existing current simulation model might include:
 The addition of the piezoviscous properties of the fluid flow through the valve at high
pressures and switching speeds
 The addition of flow forces and how they affect the high pressure performance of the
valve, especially at high switching speeds. Although flow forces are increasingly
included in dynamic models, there are two limitations that this proposed supplement will
consider.
o At high pressures the acceleration of the fluid during each switch, and resulting
pressure gradients, is different and may lead to more localized phase change,
vapor creation, etc., that is not included in current CFD algorithms. This work
will be enhanced by current research in ERC project 3.C.
o At high switching speeds the unsteady flow forces, even at normal operating
pressures, not well understood nor modeled by existing CFD codes. Recent work
has demonstrated that there are significant errors in the calculation of flow rate
phase lag and attenuation when using current commercial CFD codes and
dynamic meshes above 1 kHz [Vescova]. It is expected that due to the higher
operating pressures studied in this supplement that the errors will further diverge.
 The collection of experimental data to support the development of new simulation
algorithms under project 3.C and supplemental request section 1.
o This will also include experimental evaluation of leakage as a function of positive
sealing contact geometries and pressure, supporting the leakage modeling efforts
already in the ERC.
o Providing the center experimental data will help develop and refine new modeling
tools in the area of leakage and flow dynamics, leading to more optimal solutions
in high pressure and high speed on/off valves.
In addition to fluid changes resulting from high pressures, the mechanical loads on the digital
valve increase as well and research must be done to study how leakage, noise, weight,
compactness, and reliability are changed due to micro and macro scales of mechanical
deformation. It is necessary that high pressure components be inherently pressure balanced and
achieve reliable sealing and movement at all pressures.
B. Brief research plan and a timeline of major milestones
Tasks
 Task 1: Analysis and modeling of fluid dynamics and transient electromagnetic
properties of high speed digital valves.
 Task 2: Development of coupled electromagnetic, hydraulic, and mechanical simulation
in Matlab/Simulink to simulate valve performance when controlling pump/motor
displacement.
 Task 3: Experimental testing of high speed digital valve to confirm the theoretical fluid
and electromagnetic models.
 Task 4: Development of control algorithms using the coupled Matlab/Simulink
simulation from Year 1.


Task 5: Experimental testing of high speed digital valve control of pump/motor
displacement.
Task 6: Implementation and comparison of different control algorithms on the
experimental test bench.
Milestones
 Analytical models and equations for the simulation of the high speed fluid and
electromagnetic dynamics of the valve [6-9 months].
 A coupled electromagnetic, hydraulic, and mechanical simulation in Matlab/Simulink to
simulate valve performance when controlling pump/motor displacement [12-15 months].
 Experimental verification of a high speed digital valve to confirm and refine the
theoretical fluid and electromagnetic models [12-15 months].
 Development of control algorithms for the coupled Matlab/Simulink simulation [15-18
months].
 Implementation and testing of high speed digital valve control of pump/motor
displacement [18-24 months].
 Implementation and comparison of different control algorithms on the experimental test
bench [18-24 months].
 Implementation of digital valve and pump/motor system into one of the proposed test
bench applications (excavator or hydraulic hybrid) [24-36 months].
Significant 5 Year Milestones (contingent on continued funding):
 Development of additional coupled systems utilizing high speed digital valves for
throttle-less control of power (virtually variable displacement pumps, camless engines,
drive-by-wire actuators, etc.)
 Development of simulation toolbox (Matlab/Simulink compatible) incorporating
configurable models of high speed digital valves and common applications.
2007
ID
Task Name
Start
Finish
Jul
1
Task 1
1/1/2007
8/31/2007
175d
2
Task 2
6/1/2007
3/31/2008
217d
3
Task 3
6/1/2007
3/31/2008
217d
4
Task 4
4/1/2008
6/30/2008
65d
5
Task 5
6/2/2008
12/30/2008
152d
6
Task 6
1/1/2009
12/30/2009
260d
12/2/2006
Milestone Description
2008
2009
Duration
11/15/2007
Milestone Description
12/2/2006 - 12/9/2006
Interval Description
C. How will project results be integrated into test beds?
Jul
Jul
The prototype high speed digital valves will be implemented and tested in test bed 1 or 3 as
displacement control actuators for the pump/motors, depending on the availability of each test
bed.
D. Describe upstream and downstream dependencies
This project directly influences and is directly influenced by other projects in the ERC. Project
1.A requires more efficient pump/motors and high bandwidth actuators, both of which are
addressed in this project. The compactness effort requires components capable of efficiently
operating at higher pressures, as addressed in this project. In addition, test bed 1 and test bed 3
are both strengthened by this project. It is also possible for this project to influence the noise
issues found in project 3.B by actively controlling and canceling the pressure ripple found in
most systems. The success of this project will be in turn influenced by project 3.C, project 1.A,
and project 1.E where the simulation tools (CFD), control algorithms, and additional applications
are developed. Current CFD algorithms have difficulties with the high frequency transient flows
and the development of improved algorithms will enhance the design optimization of high speed
valves. The testing of the prototype valves will provide valuable feedback to project 3.C
personnel and can be used to validate the improved algorithms.
3. Resources
A. Expected resources required from the ERC in years 1, 2 and project completion
(Identify yr)
John Lumkes 0.5 month summer pay each year
Year 1:
 One graduate student
 S&E
 Travel
Year 2:
 One graduate student
 S&E
 Travel
Year 3:
 One graduate student
 S&E
 Travel
B. Requests from industry partner.
Prototyping of new high speed valve designs
A pump/motor for displacement control testing
Hoses, fittings, and instrumentation for experimental validation of valves
4. References
[#] Anon., “World’s First Full Hydraulic Hybrid SUV Presented at 2004 SAE World Congress,”
EPA420-F-04-019, Environmental Protection Agency, March 2004.
[#] Batdorff, M., and Lumkes, J., “Virtually Variable Displacement Hydraulic Pump Including
Compressibility and Switching Losses”, Proceedings of IMCE2006, IMECE2006-14838, 2006.
[#] Fronczak, F. J., Ma, J. S., and Beachley, N. H. Design of a High Speed, High-Flow, ThreeWay Poppet Valve, National Conference on Fluid Power 105-7.3, 223-231, 2005.
[#] Li, P. Lie, C., and Chase, T., Software Enabled Variable Displacement Pumps, Proceedings
of IMECE2005, IMCE2005-81376, 2005.
[#] Rannow, M., Ut, H., Li, P., and Chase, T., “Software Enabled Variable Displacement
Pumps—Experimental Studies”, IMECE2006, IMECE2006-14973, 2006.
[#] Vescovo, G., and Lippolis, A., “A Review Analysis of Unsteady Flow Forces in Hydraulic
Valves”, International Journal of Fluid Power, Vol. 7 No 3, 2006, pp. 29-39.
Work at Other Universities:
University of Minnesota—Twin Cities
Aachen University (Germany)
Gifu University (Japan)
Tampere University of Technology (Finland)
University of Linz (Austria)