•An innovative procedure to design a commercial proportional directional valve is shown.•Experimental tests are performed to demonstrate the flow force reduction.•The design is improved by means of a ...previously made optimization procedure.•Great reduction in the flow forces without reducing the flow rate is demonstrated.
This paper presents the experimental validation of a new methodology for the design of the spool surfaces of four way three position direct operated proportional directional valves. The proposed methodology is based on the re-design of both the compensation profile (the central conical surface of the spool) and the lateral surfaces of the spool, in order to reduce the flow forces acting on the spool and hence the actuation forces. The aim of this work is to extend the application range of these valves to higher values of pressure and flow rate, thus avoiding the employment of more expensive two stage configurations in the case of high-pressure conditions and/or flow rate. The paper first presents a theoretical approach and a general strategy for the sliding spool design to be applied to any four way three position direct operated proportional directional valve. Then, the proposed approach is experimentally validated on a commercially available valve using a hydraulic circuit capable of measuring the flow rate as well as the actuation force over the entire spool stroke. The experimental results, performed using both the electronic driver provided by the manufacturer and a manual actuation system, show that the novel spool surface requires remarkably lower actuation forces compared to the commercial configuration, while maintaining the same flow rate trend as a function of the spool position.
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•Odor concentration was slowly varied by changing the mixing ratio of a clean and an odor-saturated air stream.•The two air streams were passed through proportional valves in series ...with electronic flowmeters for feedback control of their volume flow rates.•This instrument mimics the rates of concentration changes within a slowly expanding, uniformly distributed odor plume.•Olfactory receptor neurons are highly sensitive to both the instantaneous odor concentration and its rate of change.
Concentration is a variable aspect of an odor signal and determines the operation range of olfactory receptor neurons (ORNs). A concentration increase is perceived as an odor stimulus. The role that the rate of concentration increase plays thereby has been studied with electrophysiological techniques in ORNs of the cockroach. A key prerequisite for these studies was the development of an air dilution flow olfactometer that allowed testing the same change in concentration at various rates.
The rate of concentration change was controlled and varied by changing the mixing ratio of odor-saturated and clean air by means of proportional valves. Their input voltages were phase shifted by 180° to hold the mixed air at a particular constant volume flow rate.
Using this stimulation technique, we identified, in a morphologically distinct sensillum on the cockroach’s antenna, antagonistically responding ON and OFF ORNs which display a high sensitivity for slow changes in odor concentration.
The olfactometer is unique because it enables delivering slowly oscillating concentration changes. By varying the oscillation period, the individual effects of the instantaneous odor concentration and its rate of change on the ORNs’ responses can be determined.
The olfactometer provides a new experimental approach in the study of odor coding and opens the door for improved comparative studies on olfactory systems. It would be important to gain insight into the ORNs’ ability to detect the rate of concentration change in other insects that use odors for orientation in different contexts.
Hierarchical control architectures are a common approach when hydraulic systems are under study; provided their multi-domain nature, the control scheme is commonly split into different hierarchical ...levels each one associated with a particular physical domain. This paper presents the application of a model-based control structure called Embedded Model Control (EMC) when a hierarchical scheme is implemented on an electro-hydraulic proportional valve. The overall control consists of two hierarchical loops: the inner loop is the solenoid current regulator with a closed loop bandwidth close to 1kHz. The outer loop is a position tracking control, in charge of the accurate positioning of the spool with respect to valve openings. The paper addresses the outer loop, i.e., the tracking of mechanical spool position by using the EMC. Analysis and synthesis are presented as well as experimental results obtained from a test rig provided by an industrial manufacturer.
•The outer loop of a hierarchical controller for proportional valves is designed by using the Embedded Model Control.•Design is supported by a discrete-time embedded model obtained from experimental data.•Parametric uncertainty and neglected dynamics are addressed by disturbance estimation and cancelation through the control law.•Experimental results show that the demanding requirements are achieved by the implementation of the EMC framework.
Es wird eine Methode zur sensorlosen Positionsbestimmung bei elektromagnetisch betätigten Aktoren vorgestellt. Dabei
werden basierend auf einer Signalinjektion die positionsabhängigen Parameter bei ...der injizierten Frequenz bestimmt und
daraus über ein geeignetes Modell die Position des Magnetankers ermittelt. Die Eignung des Verfahrens zur sensorlosen
Positionsregelung wird an einem bidirektionalen Proportionalventil anhand praktischer Versuche demonstriert.
optimization) optimal settings have been determined (frequency and amplitude). The optimum frequency of the Dither current intensity was compared with the value of the natural frequency of examined ...hydraulic cylinder (taking into account a hydraulic stiffness) and with the cut-off frequency of tested valve.
This paper describes the theoretical-experimental study of an auto-adjustable stroke end cushioning device utilized in hydraulic cylinders, focusing the characterization of the bush geometry effect ...on the cushioning achieved. A nonlinear model is presented which includes the physical phenomena that exert a significant influence on the performance of this hydraulic component, such as: friction, fluid compressibility and pressure energy loss in the cushioning section. The model is validated through the comparison between theoretical and experimental results, under different conditions of load, supply pressure and piston speed. From this point it is possible to obtain a model applicable for the design of stroke end cushioning devices in hydraulic cylinders. Consequent contributions related to proportional directional valves modeling are also presented.
Fluid power systems are manufactured by many organizations for a very wide range of applications, which often embody differing arrangements of components to fulfill a given task. Hydraulic components ...are manufactured to provide the control functions required for the operation of a wide range of systems and applications.
A nonlinear dynamic model of a Honeywell Lucifer-type EPP3 J-21-U-100-10 (now Parker P3P-R) pneumatic proportional pressure valve is formulated by modeling the valve's main internal mechatronic ...devices in order to simulate its dynamic behavior in the time and frequency domains, for several operating conditions and different downstream loads. Mechatronic design and functionality of this valve are carefully analyzed by considering the conditions of its internal devices for each of the three standard working configurations of a three-way proportional valve. The main physical parameters introduced in formulating the dynamic model were identified by means of an experimental investigation. Finally, the experimental and simulated diagrams in the time and frequency domains are compared in order to validate the proposed model, which can be used as a general approach for modeling any pneumatic proportional pressure valve featuring a similar mechatronic design and internal structure.
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