Proportional Solenoid Valve Research Articles

Servo-controlled pneumatic pressure oscillator for respiratory impedance measurements and high-frequency ventilation.

The ability to provide forced oscillatory excitation of the respiratory system can be useful in mechanical impedance measurements as well as high frequency ventilation (HFV). Experimental systems currently used for generating forced oscillations are limited in their ability to provide high amplitude flows or maintain the respiratory system at a constant mean pressure during excitation. This paper presents the design and implementation of a pneumatic pressure oscillator based on a proportional solenoid valve. The device is capable of providing forced oscillatory excitations to the respiratory system over a bandwidth suitable for mechanical impedance measurements and HVF. It delivers high amplitude flows (> 1.4 l/s) and utilizes a servo-control mechanism to maintain a load at a fixed mean pressure during simultaneous oscillation. Under open-loop conditions, the device exhibited a static hysteresis of approximately 7%, while its dynamic magnitude and phase responses were flat out to 10 Hz. Broad-band measurement of total harmonic distortion was approximately 19%. Under closed-loop conditions, the oscillator was able to maintain a mechanical test load at both positive and negative mean pressures during oscillatory excitations from 0.1 to 10.0 Hz. Impedance of the test load agreed closely with theoretical predictions. We conclude that this servo-controlled oscillator can be a useful tool for respiratory impedance measurements as well as HFV.

PROPORTIONAL SOLENOID CONTROL PRESSURE RELIEF VALVE: PERFORMANCE STUDY THROUGH MODELLING, SIMULATION AND EXPERIMENT

The dynamic characteristics of a proportional solenoid control single stage pressure relief valve is studied theoretically through modeling and simulation, supported by existing experimental result. Based on an existing model for the estimation of pressure loss coefficients the overall steady state pressure flow characteristics of the valve are determined. A detailed dynamic model has been developed and studied within the MATLAB-SIMULINK environment. The nonlinearities have been considered via the use of appropriate SIMULINK blocks. Detail valve geometry is considered in order to model the valve accurately. The solenoid is modelled as a nonlinear resistor/inductor combination. The spool valve assembly is modelled as a spring/mass/damper system with the consideration of inertia and damping effects. The inductance parameters are described as a function of displacement and current. The detailed modelling has resulted in a good comparison between simulation and measurement. The overall dynamic behaviour has been shown to be dominated by the solenoid characteristic relating force to applied voltage.

A parsimonious model for the proportional control valve

A generic non-linear dynamic model of a direct-acting electrohydraulic proportional solenoid valve is presented. The valve consists of two subsystems—a spool assembly and one or two unidirectional proportional solenoids. These two subsystems are modelled separately. The solenoid is modelled as a non-linear resistor-inductor combination, with inductance parameters that change with current. An innovative modelling method has been used to represent these components. The spool assembly is modelled as a mass-spring-damper system. The inertia and the damping effects of the solenoid armature are incorporated in the spool model. The model accurately and reliably predicts both the dynamic and steady state responses of the valve to voltage inputs. Simulated results are presented, which agree well with experimental results.

Proportional assist ventilation system based on proportional solenoid valve control

A new proportional assist ventilation (PAV) method using a proportional solenoid valve (PSV) to control air supply to patients suffering from respiratory disabilities, was studied. The outlet flow and pressure from the proportional solenoid valve at various air supply pressures were tested and proven to be suitable for pressure and flow control in a PAV system. In vitro tests using a breathing simulator, which has been proven to possess the general characteristics of human respiratory system in spontaneous breathing tests, were conducted and the results demonstrated the viability of this PAV system in normalizing the breathing patterns of patients with abnormally high resistances and elastances as well as neuromuscular weaknesses. With a back-up safety mechanism incorporated in the control program, pressure ‘run-away’ can be effectively prevented and safe operation of the system can be guaranteed.

Fault Detection of a Solenoid Valve for Hydraulic Systems in Vehicles

In passenger and utility vehicles proportional solenoid valves are used in different hydraulic systems. The valves often have an important impact on the operation quality of succeeding components. However, the correct functioning of the devices is only insufficiently checked. Therefore a novel, model-based approach is going to be presented which is able to estimate the solenoid’s armature stroke based on measured voltage und current. No expensive position sensor is required, that could reduce the overall reliability. Evaluating the reconstructed stroke, faults such as blockade, increased friction, etc. can be detected. But also faults in the electrical part of the valve may be isolated. Instead of replacing whole components in case of a faulty behaviour, the self check of the solenoid valve itself can assist in judging whether the component or the solenoid is faulty. Hence, maintenance costs can be optimized.The paper includes experimental results. Aspects of the microcontroller implementation are addressed.

Comparison of Sliding Mode Control With State Feedback and PID Control Applied to a Proportional Solenoid Valve

A novel nonlinear sliding mode controller has recently been developed for direct acting proportional solenoid valves. This paper presents a comparison between the valve performance using this controller, and that obtained using two alternative control strategies; state feedback and PID control. Each controller is described in turn, and experimental step response results are presented to demonstrate the validity of each strategy. These results are compared on the basis of response time, overshoot, and steady-state error. The time taken to design each controller, and the required level of knowledge of the valve dynamics, are also assessed. The ability of each controller to reject flow reaction forces is evaluated by observing the changes in the step response when oil is passed through the valve. The results demonstrate that the sliding mode controller results in a faster, more robust closed-loop response. In addition, only minimal knowledge of the valve dynamics is required in order to design the controller.

The Modeling and Simulation of a Proportional Solenoid Valve

A nonlinear dynamic model of a high speed direct acting solenoid valve is presented. The valve consists of two subsystems; a proportional solenoid and a spool assembly. These two subsystems are modeled separately. The solenoid is modeled as a nonlinear resistor/inductor combination, with inductance parameters that change with displacement and current. Empirical curve fitting techniques are used to model the magnetic characteristics of the solenoid, enabling both current and magnetic flux to be simulated. The spool assembly is modeled as a spring/mass/damper system. The inertia and damping effects of the armature are incorporated in the spool model. The solenoid model is used to estimate the spool force in order to obtain a suitable damping coefficient value. The model accurately predicts both the dynamic and steady-state response of the valve to voltage inputs. Simulated voltage, current, and displacement results are presented, which agree well with experimental results.

比例電磁弁の性能改善について

比例電磁弁の性能改善について

Computer-assisted guiding system of multi-jointed pile driver arm

In big cities such as Tokyo, the number of urban renewal and infrastructure development projects is on the increase. Because of restrictive work site conditions in urban areas, compact construction machines with high mobility are favored.To meet this need, we developed a new type of pile driving machine: the HITACHI RX 2000. With this machine, a piling attachment is directly connected to the tip of the multi-joined pile driver arm, and the computer-assisted guiding system allows precise piling work to be done. We call this new system “arm tip locus control.”The system is basically a combination of proportional solenoid valves, a microcomputer, and sensors. However, many state-of-the-art innovations were employed in order to achieve precise arm tip locus control.

A microcomputer-based agricultural digger control system

Considerable skill is required to operate an agricultural digger accurately and efficiently, and an analysis of the different procedures and operator skills is given. From this a specification of a microprocessor-based control system for a tractor-mounted digger is derived to give: linear bucket blade movement, accurate gauging of the pitch of sloping cuts, and a learn-and-repeat facility. A closed-loop control system is described using an 8085A microprocessor with an AM9511 arithmetic processor for real-time floating-point calculation. Precision potentiometers were used for position feedback and proportional solenoid valves for control of the hydraulics. A firmware option also allowed the system to be operated open loop to emulate a conventional digger. For novice users the cutting of straight profiles was facilitated but the time for digging operations showed no consistent improvements. This is probably because the decision-making process in lever selection is not eliminated and a telechiric system would be more effective. The open-loop system has the advantages, over conventional mechanical control, of ease of installation and reduced lever loads.