Movable electrode-type ER actuators (proposal of linear-type and rotary-type METERA)
By employing ER fluids as working fluids in fluid power systems, a direct interface can be realized between electric signals and fluid power without the need for mechanical moving parts like spools in control valves. In the paper, first, hydraulic actuators with ER fluids and with movable electrodes (METERA: movable electrode-type ER actuator) are proposed, which are classified into a linear type (L-METERA) and a rotary-type (R-METERA). Secondly, a design method of L-METERA is described and a small sized L-METERA is fabricated, whose size is 40 mm/spl times/18 mm/spl times/16 mm. Thirdly, a design method of R-METERA is described and a small sized R-METERA is fabricated, whose size is /spl phi/67 mm/spl times/53 mm. Principles of METERA are confirmed with the fabricated METERA.
Electro-rheological valves in a hydraulic circuit
An electro-rheological (ER) or ‘smart’ fluid changes from a fluid to a solid when a high electric field is applied to it. The effect is reversible and can be used in hydraulic valves with no moving parts and fast response times. One way to utilise the effect is presented. A simple equation to predict the controlled power is derived.
Identifying the optimum water flow and number of buckets in laboratory-scale Pelton turbine using Central Composite Design (CCD)
Pelton turbines were a type of water turbines which, principally, turned the water kinetic energy into electrical energy. The working principle of Pelton turbines was to utilize water power to produce turbine power. This paper reported the optimization of design parameters for laboratory-scale Pelton turbine using the central composite design (CCD) as the response surface methodology (RSM). This research obtained the quadratic polynomial equations for the turbine power. The independent variables were water flow (0.11 m3/s; 0.13 m3/s; 0.15 m3/s) and number of buckets (13; 15; 17 pieces). The results, based on the RSM, showed that the most influential parameter on the turbine power was the number of buckets. The optimum turbine power was 24 kW on 0,16 m3/s water flow and 18 buckets of RSM.