No abstract

A piston piezoelectric (PZT) pump has many advantages for the use of light actuators. How to deal with the contradiction between the piston amount and oil delivery quality is an essence when designing the pump. In order to depress the pressure pulsation and flow pulsation in a single-piston PZT pump, a two-stage attenuator is proposed. It involves an elastic cavity group and an unloading valve. Unsteady flow inside the pump is numerically calculated and analyzed to reveal its delivery characteristic in the whole pumping cycle. The distributing process of the passive valves is obtained through the dynamic mesh technique. Influences of key design and operation factors on the delivery performance of the pump are analyzed. The results indicate that the flexible cavity group and the unloading valve arranged at the delivery port can reduce the flow pulsation by 45%. The design can effectively provide stable flow for the actuator in a certain frequency range.

Purpose The purpose of this paper is to provide a new hydrostatic actuator controlled by a piezoelectric piston pump and to reveal its characteristics. Design/methodology/approach In this paper, a piezoelectric pump with passive poppet valves and hydraulic displacement amplifier is designed as a new control component in a hydrostatic actuator for high actuation capacity. A component-level mathematical model is established to describe the system characteristics. Simulation verification for cases under typical conditions is implemented to evaluate the delivery behavior of the pump and the carrying ability of the actuator. Findings By using the displacement amplifier and the passive distributing valves, simulation demonstrates that the pump can deliver flow rate up to 3 L/min, and the actuator controlled by this pump can push an object weighing approximately 50 kg. In addition, it is particularly important to decide a proper amplification ratio of the amplifier in the pump for better actuation performance. Originality/value The piezoelectric pump presented in this paper has its potential to light hydrostatic actuator. The model constructed in this paper is valid for characteristic analysis and performance evaluation of this pump and actuators.

In this paper, a piezoelectrically driven single piston pump is designed for high delivery pressure and large displacement. It is composed of a piezoelectric stack, a hydrostatic amplifier and a plunger with two check valves from a radial plunger pump commercially available. Passive check valves instead of active membranes in the pump allow higher pressure delivery, and the hydrostatic amplifier is adopted for larger displacement of the pump. In order to study delivery characteristic of a piezoelectrically driven single piston pump, numerical simulation of unsteady flow inside the pump is conducted by computational fluid dynamics (CFD). Moving mesh technique is adopted to characterize the behavior of two check valves for oil distributing. Influences of typical design and operation parameters on delivery performance of the single piston piezo pump are analyzed. The results show that, driving frequency and spring stiffness of the valves and chamber configuration should be properly designed for stable oil delivery with low flow ripple as possible. Numerical simulation is valid to describe the behavior of the pump, on target for theoretical reference to its counterparts used in miniature EHA actuators.

No abstract