Magnetorheological Hydraulic Actuator Driven by a Piezopump

Abstract

Magnetorheological (MR) fluids can be used in a variety of smart semi-active systems. The MR damper shows an especially great potential to mitigate environmentally induced vibration and shocks. Another aspect of MR fluids is the construction of MR valve network in conjunction with a hydraulic pump resulting in a fully active actuator. These devices are simple, have few moving parts and can be easily miniaturized to provide a compact, high energy density pressure source. The present study describes a prototype MR-piezo hybrid actuator that combines the piezopump and MR valve actuator concepts, resulting in a self-contained hydraulic actuation device without active electromechanical valves. Durability and miniaturization of the hybrid device are major advantages due to its low part count and few moving parts. An additional advantage is the ability to use the MR valve network in the actuator to achieve controllable damping. The design, construction and testing of a prototype MR-piezo hybrid actuator is described. The performance and efficiency of the device is derived using ideal, biviscous and Bingham-plastic representations of MR fluid behavior, and is evaluated with experimental measurements. This will provide a design tool to develop an actuator for a specific application.

Development of piezohydraulic actuator driven by piezomembrane pump

“…Taking the hydraulic actuators driven by passive-valve piezopumps for examples, blocking force of 155.6 N at 100 Hz and velocity of 3.05 cm/s at 300 Hz have been reported by Sirohi and Chopra (2003), and blocking as high as 271 N and velocity of 7.25 cm/s at 800 V and 60 Hz were also reported by Mauck and Lynch (2000). With magnetorheological valves control, the piezohydraulic actuator achieved an output velocity of 0.534 cm/s against a mass load of 515 N at 250 Hz (Yoo et al, 2003). Compared with the conventional piezoelectric linear motors, the piezohydraulic actuators prefigure desirable performance, such as long working life (no wear failure), high holding force without power, no jerk/impact, and low machining precision required.…”

“…Different from principles and structures of the conventional contact/non-contact piezoelectric motors, the piezohydraulic actuators are actually hydraulic cylinder systems actuated by piezostack pumps with different types of check valves. Thus, the dynamic characteristic and output capability of the hydraulic actuators depend also on types of valves, such as magnetorheological liquid valves (Yoo et al, 2003(Yoo et al, , 2005, passive check valves (Mauck and Lynch, 2000;Lindler and Anderson, 2003;Sirohi and Chopra, 2003;Tang et al, 2009;Kan et al, 2010), and active valves (Tan et al, 2005). The common characteristics of the mentioned piezohydraulic actuators are that they are able to achieve large output force, high velocity, and long traveling distance at the same time.…”

Compact actuation through magnetorheological flow control and rectification of magnetostrictive vibrations

“…The total flow volume divides into two fluid paths connected in parallel while observing conservation of mass laws (13) and (14). Q R is the volume flow rate of MR fluid through the right valve half and output piston, and Q L is the volume flow rate through the left valve half.…”

“…11 While MR fluids are being increasingly used commercially in automotive and seismic dampers, 12, 13 novel actuator concepts based on these fluids are scarce. 14,15 This paper implements the controllable rheological behavior of MR fluid coupled with the giant magnetostrain of a Terfenol-D MR fluid pump in a new hybrid actuator design. The combination of giant magnetostrain and robust operation make Terfenol-D particularly well suited for driving a piston-type fluid pump.…”