DESIGN AND VALIDATION OF ELECTRO-HYDRAULIC PRESSURE-CONTROL VALVES FOR CLOSED-LOOP CONTROLLER IMPLEMENTATION

Abstract Electro-hydraulic pressure-control valves are used in many applications, such as manufacturing equipment, agricultural machinery, and aircraft. A traditional electro-hydraulic pressure-control valve regulates an output pressure for a corresponding input current by balancing solenoid force, spring force, and regulated pressure force. This results in a repeatable steady-state pressure output that is nearly proportional to the input current. This is helpful to achieve a consistent output pressure for a corresponding input current in open loop applications. However, the transient pressure response is highly sensitive to the component tolerances and manufacturing processes as well as the fluid properties in the regulated volume. These properties are often unknown in a system and can vary significantly from system to system and also during use, making controllability difficult. Since there is variation in the steady-state pressure output for a given valve population, these valves are often calibrated in the end system to achieve the desired output. Nonetheless, there is variation in the preceding process, and also variation within a single valve over life; thus closed loop control is desirable. Unfortunately, attempts at closed loop control of a traditional pressure-control valve often yields unacceptable performance. This is due to the sensitivity of the transient response to system characteristics, primarily fluid and mechanical properties.  This work investigates dynamic valve modeling, the development of valves with more consistent transient performance, and closed loop control of these new valves.

Contact: richard.meyer@wmich.edu or carey.schoolmaster@wmich.edu