• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.3
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• pp.82-89
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• 2009

The purpose of this study is to investigate the actual field application of the linear piston pump for the solid transferring driven by the hydraulic power unit. In this paper, the numerical analysis and performance evaluating experiments were performed. CFX program has been used to obtain the solutions for the problems of three-dimensional, turbulent water flow in the linear piston pump. The velocity and the pressure distributions are obtained using the turbulent $k-\varepsilon$ model. To evaluate the performance of the linear piston pump, the performance test stand and data acquisition system were manufactured. The numerical predictions agree favorably with experimental results within 7% error. Speed of the piston which is satisfied the flow rate 3,000l/min which considers from basic design became 0.33m/s. This paper could be applied to the design of the linear piston pump for the fish transferring.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2535-2542
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• 2000

The regulator system has been modeled and combined to a swashplate type axial piston pump. Linear approximation has been performed for nonlinear coefficient terms of an axial piston pump-regulator model without significantly affecting accuracy. Based on the mathematical model of an axial piston pump-regulator system, a couple of characteristic curves of negative flow control and horsepower control are drawn, which show a good correlation with those of experimental results. So the simplified axial piston pump-regulator model in this paper is expected to be utilized not only for the design and analysis of hydraulic circuit of excavator but also for prevention of engine overload.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.156-158
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• 2008

Along the various gap distance between shoe and swash plate and pocket diameter, lifting force of piston shoe during the compressing stage was calculated. The flow in piston, orifice, shoe, and back space was considered to be 2-dimension axisymmetric and analysed by Fluent, a commercial CFD Software. The wall boundary condition was given as nonslip and adiabatic, while the change in fluid viscosity was considered as linear along temperature. Calculated lifting force and oil leakage of shoe was used in the design of a pump to confirm the shape of the shoe.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.165-174
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• 2007

Variable displacement type piston pump uses various controllers for controlling more than one state quantity like pressure, flow, power, and so on. These controllers need the mathematical model closely expressing dynamic behavior of pump for analyzing the stability of control systems which usually use various kinds of state variables. This paper derives the nonlinear mathematical model for variable displacement type piston pump. This model consists of two 1st oder differential equations by the continuity equations and one 2nd oder differential equation by the motion equation. To simplify the model we obtain the linear state variable model by differentiating the three nonlinear equations. And we verify this linearized model by comparison of simulation with experimentation and analyze the stability for the flow/pressure control. Finally this paper suggests the design compensation to ensure the stability of the systems.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.2
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• pp.228-236
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• 2021

In order to understand the underwater noise source factor of the linear pump type forced ejection system, a reduced-model compressed water experiment device was developed. The reduced-model compressed water experiment device consists of a reverberation tank, a linear pump type forced ejection device, and an underwater vehicle. The underwater noise source was selected from the hydraulic ram moving speed, the hydraulic ram/piston pipe spacing, the ejection pipe inlet/water ram area ratio, and the number of water ram inlets. The underwater vehicle was ejected into the reverberation tank by the device. The source level was derived from the measured sound pressure. The source level tends to increase as the hydraulic ram/piston tube spacing and the hydraulic ram moving speed increase. The source level tended to increase as the area ratio was increased, but the level was weak. The number of water ram inlet did not affect the source level.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.680-683
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• 2002

In this paper, it has been investigated that the design and simulation of vacuum pump driven by linear motor. Vacuum pump consists of unified plunger and piston part, coils, inlet valve and outlet valve. Operating principal of vacuum pump show that air is to flow to go inside through the inlet valve when the magnetic force (16N) is exerted, whereas, air is to flow to go outside through outlet valve when spring farce (14.8N) is exerted. The results of simulation. it was turned out that reached vacuum pressure was about -0.55 bar at 150 seconds, magnetic force was loaded with 16 Newton, displacement of actuator was about 8mm.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2683-2686
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• 2002

In this paper, it has been investigated that the design and simulation of linear motor for medical appliances. Vacuum pump consists of unified plunger and piston part, coils, inlet valve and outlet valve. Operating principal of vacuum pump show that air is to flow to go inside through the inlet valve, when the magnetic force (16N) is exerted, whereas, air is to flow to go outside through outlet valve, when spring force (14.8N) is exerted. The results of simulation, it was turned out that magnetic force was loaded with 16 Newton, displacement of actuator was about 8mm.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.2
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• pp.255-265
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• 2019

In the present study, the effect of opening patterns of a flow control valve on underwater discharge systems using a linear pump was investigated numerically. For that, a improved mathematical model was developed. The improvement is to separate a middle tank from a water cylinder because the cross-section area of the inlet of the middle tank is an important parameter. To validate the improved model, calculation results were compared with a previous study. The results showed that $2^{nd}$ order or more polynomial opening patterns had an advantage over ramp opening patterns. Higher an order of polynomial resulted in wider operating limits. An escape velocity and a maximum acceleration of underwater vehicle were affected by time derivative of the cross-section area of the flow control valve. Besides, as a velocity profile of the vehicle got closer to linearity, the escape velocity got faster and the maximum acceleration got smaller. And velocities of the vehicle and piston had similar variation trend.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.2
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• pp.219-227
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• 2021

In the present study, the effect of command signals of the flow control valve on performance of underwater discharge systems using a linear pump was investigated numerically. For that, the improved mathematical model was developed. The improvement is to calculate the flow leakage between the water cylinder and the piston. Also the model of the hydraulic cylinder is simplified. To validate the improved model, calculation results were compared with experiment results. The results of the study is as follows: Double ramp command signals of the flow control valve had an advantage over single ramp signals. The parametric study on the effect of double ramp command signals on performance of the system was performed. In case of using double ramp signals, the maximum acceleration of the underwater vehicle was reduced by approximately 50 % compared with using single ramp signals.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.160-170
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• 2006

If hydraulic pump controlled by mechanical type regulator has more than one control function, the construction of regulator will be very complicated and control performance falls drastically. It is difficult to have more than one control function for hydraulic pump controlled by electronic type hydraulic valve due to the inconsistency of controllers. This paper proposes a multi-function control technique which controls continuously flow, pressure and power by using EPPR(Electronic Proportional Pressure Reducing) valve in swash plate type axial piston pump. Nonlinear mathematical model is developed from the continuity equation for the pressurized control volume and the torque balance for the swash plate motion. To simplify the model we make the linear state equation by differentiating the nonlinear model. A reaction spring is installed in servo cylinder to secure the stability of the control system. We analyze the stability and disturbance by using the state variable model. Finally, we review the control performances of flow, pressure and power by tests using PID controller.