• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.472-477
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• 1994

The lockup clutch is embeded on torque converter of automatic transmission to prevent the efficiency deterioration of torque converter in high speed. For improving fuel consumption rate, it is desirable to engage the lockup clutch earlier. But, it results in degrading shift quality, due to the transient torque. The transient clutch pressure which affects the shifting quality, should be controlled properly. In this study, to solve the problem, it is analysed the hydraulic circuit of lockup system including line pressure regulating circuit, established the nonlinear model, and designed the PID controller. The line pressure is supplied to the lockup clutch through the lockup control valve by switching the lockup solenoid valve on. In order to control the transient pressure actively, it is needed to control the lockup solenoid valve by closed loop control. The lockup solenoid valve is 2-way on-off valve, and is adequate for PWM control. To reduce the pressure chattering, the carrier frequency is increased. Target pressure profile is computed from optimized velocity difference profile throuth dynamic equation of vehicle system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.78-84
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• 2017

Compared to other types of power, hydraulic energy is the most commonly used for heavy vehicles and ships because it has fewer location and space constraints, and its controllability can be maintained even under adverse conditions. Operators have controlled a main control valve of ship winches by pushing or pulling the lever, which is directly connected to the spool. However, because of the spatial arrangement, the importance of remote control valves has emerged. In this paper, experiments of the hysteresis characteristics were performed by analyzing the remote-control valve using a valve tester and RA2300. The validity was verified by comparing with the analytical model using SimulationX as the hydraulic analysis program. This study examined the effects of the spool's notch (Non, End-mill, and Spherical) and the effects of stiffness and pre-load of the spool spring on Spool stroke, open area, and hysteresis characteristics. It is considered possible to reduce the cost and the, trial and error process in designing remote-control valves in the future.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.80-85
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• 2003

In the present paper, dynamics analyses of pressure control characteristics have been performed in a variable pressure solenoid valve. A number of solenoid valves have been used in the electronic control system, especially automatic transmission of an automobile. Variable pressure solenoid valve is intended to produce spatial movement by the electrical signal. Dynamics analyses of pressure control characteristics have been practiced by the Finite Difference Method, which show the pressure distribution in the solenoid valve. The results of numerical analyses show the dependence of pressure distribution on the displacement of the spool in the solenoid valve, and then, are compared with the experimental results.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.389-394
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• 2017

The limitation of flow control for a bistable fluidic valve has been investigated. The physical model of the fluidic valve includes two main flow outlets and two control flow inlets. The experiments were conducted with pressure regulators, mass flow meters, and piezo sensors to analyze flow switching characteristics of the fluidic valve. The experimental data such as pressure and mass flow rate of control flows and the switching time of the main flow was obtained with various operating conditions. The operation limit of the fluidic valve is identified, and a model equation for pre-estimating the minimum control pressure to switch the direction of the main flow has been proposed.

• Journal of Power System Engineering
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• v.20 no.3
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• pp.36-42
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• 2016

A cylinder control system of the conventional construction machine has been controlled by hydraulic spool valves. This system is low-cost but system efficiency is not high. Recently, to improve this, all valves are controlled electronically and independently. Bu and Yao suggested four way electronic hydraulic control valve system. It is called IMVT(Independent Metering Valve Technology). The purpose of the study is to find proper IMV pressure control method for excavator and to validate excavator's bucket regeneration energy effect by controlling the IMV system. In this paper, we mathematically describe the bucket system of excavator first. And then, based on these results, we design the control system which is divided into two operations(none regeneration or regeneration).The results of the experiment show the desirable performance and usefulness of the designed control system.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.136-136
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• 2000

The direct drive servo valve(DDV) is composed of a DC rotor, link, valve spool and displacement sensor(LVDT) where the spool is directly coupled to the DC motor through the link. Since the DDV is a kind of one-stage valve, the robust controller is required to overcome the flow force effect on the spool motion. The mathematical equations are derived and the stability, accuracy and response speed of a DDV are investigated analytically using a linearized system block diagram. Proportional control, PID control. Time-Delay control, Sliding Mode control, and Proportional control using the load pressure are applied to DDV to find which one shows the best control performance. The digital computer simulation results show that the proportional control using the load pressure satisfies the design requirement of response speed and steady state error regardless of the variation of load pressure,

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.429-436
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• 2007

In this study, we improved control performance of an EMV (electromechanical valve) system using a PM/EM (permanent magnet/electromagnet) hybrid EMA (electromagnetic actuator) and showed the feasibilities of both soft landing and fast transition of the EMV system using a simple PID control. The conventional EMV systems using only EM show significant nonlinear characteristics. Therefore, it is very difficult to control the valve position and several complex control schemes are used. This paper focused on the control performance improvement using a PM/EM hybrid actuator. In particular, a PM is used as a key design parameter such as a bias current of a magnetic bearing in order to improve the linear characteristic of the actuator, although most PM/EM hybrid actuators use a PM as a power saver during valve-open and -closed states. First, a FE (finite element) analysis was performed to confirm its linear static force characteristics. Then, both a test rig and a valve control system were built in order to prove experimentally the control performance improvement of the actuator. Finally, feasibilities of both soft landing and fast transition of the system were shown experimentally through gain-scheduled PID (proportional derivative integral) control.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.923-930
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• 2008

The butterfly valve is widely used in the industrial field as an on-off or a flow control valve. When the butterfly valve is used as a flow control valve. cavitation sometimes occurs in the range of high flow rate because of the small valve opening. Therefore. the pressure loss and the cavitation characteristics are investigated by use of a commercial CFD code. The results show that the possibility of cavitation occurrence in the cryogenic butterfly valve is very high in the case of valve opening angle below 10 degree and incident velocity over 6m/s. By increasing the inlet velocity at 10 degree of valve opening angle. the value of loss coefficient increased. However. by increasing the inlet velocity at 50 degree of valve opening angle. the value of loss coefficient decreased.

• Journal of Power System Engineering
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• v.12 no.2
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• pp.62-70
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• 2008

The paper made a description of the method for numerical analysis and modeling of a proportional pressure control valve by bondgraph. The valve is a three port pressure regulator valve, consists of two subsystems; a proportional solenoid and a spool assembly. A purpose of this study is to analysis the dynamic characteristics of the valve using bondgraph method and to verified results that each of parameters has an effect on modeling. It considered the effect which the presence of solenoid, flow coefficient and non-linearity of resistance causes in the valve modeling. In particular, it is analyzed the effect that the solenoid interacted with modeling results and characteristics of the nonlinear resistance through orifice on the supply and discharge side of valve. Thus this paper described method to present nonlinear characteristics by bondgraph modeling method, so that we could know easily result that each parameters has an effect on the modeling.

• Journal of Drive and Control
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• v.15 no.4
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• pp.61-66
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• 2018

Almost every hydraulic system is equipped with a pressure relief valve, to maintain working pressure of the system at a pre-determined level. Thus, dynamic characteristics of such a relief valve, in conjunction with other hydraulic components, are important in designing the hydraulic control system. The single stage pressure relief valve is dynamically undesirable, due to relatively low viscous damping, that causes high frequency oscillations. This problem is overcome by introducing orifices in the inner pilot line, and drain line. In this study, for the single stage spool type pressure relief valve, the system equations were derived through an adequate linearisation and several simplifications were made, to use the transfer function formulation technique. All coefficients were evaluated and used, to make some results by using Matlab software. Results of analysis are compared with experimental results. In this study, parameters affecting stability of valve design are determined and suggested relative to the design.