• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2003년도 학술대회지
• /
• pp.329-334
• /
• 2003

Design of pre-compression region(trapping region) of the valve plate is an important element to minimize the pressure fluctuation in a cylinder and in discharge process, and pump noise. In this study, we tried to prove what the characteristics of the oil hydraulic pump would be according to the angle of the trapping region. Three kinds of asymmetrical valve plates were used. As a result, we found that by designing the trapping region, the slope of the pressure rise in the cylinder port from low-pressure suction region to high-pressure discharge region is relaxed and the pressure fluctuation width and the discharge pressure pulsation are reduced. Therefore, because the pump gets smooth pressure fluctuation and low fluid Impact, the pump noise is reduce.

• International Journal of Fluid Machinery and Systems
• /
• 제1권1호
• /
• pp.109-120
• /
• 2008

An innovative method of changing a centrifugal low specific speed pump performance and pressure fluctuation by applying outlet flaps to impeller exit has been investigated. The outlet blade edge section corresponds to the trailing edge of wing on the circular-cascade, which dominates the pump performance and pressure fluctuation. Computational fluid dynamics (CFD) analysis of the entire impeller and volute casing and an experimental investigation are conducted. The pressure fluctuation and the vibration of the shaft are measured simultaneously. Kurtosis is applied as a dimensionless parameter with which the unevenness of velocity distribution at impeller outlet is indicated. The influence of the flaps on the pressure fluctuation is explained by the kurtosis. This paper presents a theoretical method of predicting the pump performance related to the attachment of a flap at impeller outlet.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.150-151
• /
• 2007

In hydraulic oil pump system, pressure has a linear relationship with output torque of motor. Torque control of pump drive can easily output stable pressure, and it can retain required pressure at minimum speed to save power consumption. Switched reluctance motor(SRM) has many advantages such as low cost and low inertia. It can generate high torque at low speed. But inherent high torque ripple of SRM influences performance of pressure control in hydraulic oil system. This paper presents direct instantaneous torque control(DITC) of hydraulic oil pump system. DITC method can reduce inherent torque ripple of SRM, and output smoothing torque to load. So the proposed hydraulic oil pump system can support smooth pressure and fast dynamic power supply to the hydraulic pump system. At last the proposed hydraulic oil pump system is verified by computer simulation and experimental results.

• 한국기계가공학회지
• /
• 제20권10호
• /
• pp.56-62
• /
• 2021

In this study, a cavitation occurrence in a piston-pump inlet was investigated by simulating the pressure distribution, according to the inlet shape of a variable-displacement swash-plate piston pump that supplies high-pressure oil to control the hydraulic system of a marine engine. Two types of pump inlets with different shapes were cast into impression models, and the models were reverse-engineered by 3D scanning. Then, the hydraulic-pressure distribution was analyzed through finite-element analysis. The results of the analysis confirmed that cavitation occurs more easily in the inlet with a steeper slope during pump operation because the inlet pressure on the valve plate is lower than that of the other pump with a gentler inlet slope.

• 한국압력기기공학회 논문집
• /
• 제13권1호
• /
• pp.69-74
• /
• 2017

In the fire protection system or fire fighting water supply system, the jockey pump is generally installed for the prevention of the pressure decrease of pipes, the frequent driving of the fire pump and protection the pipes from the water hammer. In this paper, the pressure-rise in fire fighting water distribution pipes in condition of pipe pressurization by the surge tank at the start-up and the sudden-stop of the fire pump without additional installation of jockey pump is considered by using simple formula calculations and the evaluation of water hammer occurrence in condition of pipe pressurization by the surge tank is included. As a result, the pressure-rise of pipes is less than the pipe design pressure at the condition of pump's start-up and sudden stop, and the possibility of water hammer occurrence is remarkably low due to pressurization of the pipes by the surge tank.

• 대한기계학회논문집B
• /
• 제28권4호
• /
• pp.406-414
• /
• 2004

In Gerotor pump, the pressure pulsations which occur due to the pump geometry result in vibration and noise of pump elements as well as cavitation in hydraulic system when the chambers of gerotor enter the delivery port and leave the suction port. Therefore it is important to study on the pressure pulsations before design and analysis of characteristics in Gerotor pump. In this paper, to reduce the unnecessary pressure pulsations, the port plate of Gerotor pump is designed based on the notch of the vane pumps and the relief grove of the piston pumps. The theoretical analysis of the pressure pulsations is performed in consideration of design parameters of the port plate which include each port positions and groove width and operating conditions which include rotational velocity and delivery pressure.

• 한국수소및신에너지학회논문집
• /
• 제31권1호
• /
• pp.89-95
• /
• 2020

The main scope of this paper is to see if the conventional pump can be properly used for a specific fuel, Di-methyl Ether (DME) despite of its low lubricity and high reactivity in the experimental conditions. A wobble plate type fuel pump was connected to the common rail to verify that the pump could deliver the fuel at the required pressure and resultantly DME could be used as fuel without modifying the original pump. At each required pressure (30 Mpa, 35 Mpa, 40 Mpa, 45 Mpa, and 50 Mpa), the pump met the pressure required by the common rail. In addition, pump performance experiments tended to follow the usual performance curve while the flow rate decreased as the pressure increased. The maximum flow rate of the pump was 470 kg/h at 30 Mpa and all measurements were taken with keeping DME temperature below 60℃.

• 한국화재소방학회논문지
• /
• 제30권2호
• /
• pp.106-113
• /
• 2016

초고압 용적형 펌프는 로터의 회전에 의한 주기적인 용적의 변화를 이용하는 펌프로 고압, 고유량을 동시에 만족하며 로터의 저속 및 고속 회전에 따라 변화 없이 일정하게 상대적으로 높은 펌프 효율을 유지할 수 있는 장점을 가진다. 많이 사용되고 있는 원심펌프와는 달리 별도의 진공펌프가 없이도 자흡 성능을 가지고 있으며, 비교적 단순한 구조로 인하여 경량화, 소형화가 가능한 특성을 자기고 있다. 유체를 높은 압력으로 이송할 수 있으며, 압력의 변동에 따라 유량의 변동이 적은 정량 토출이 가능하다. 이러한 용적형 펌프를 사용하는 이유는 흡입된 유체가 유량의 변화 없이 토출되는 장점이 있기 때문이다. 본 연구에서는 유량의 변화가 없다는 장점이 있는 용적형 펌프의 체절시스템을 개발하여 펌프의 고압 운전시의 안전성을 확보하고자 하였다. 체절시스템은 컨트롤러 프로그램, 전자클러치, 릴리프밸브의 3가지로 이루어져, 한 가지 시스템이 작동하지 않아도 다른 시스템이 작동하는 시스템으로 이루어져 있다. 컨트롤러 프로그램과 전자 클러치의 작동을 확인하기 위한 과속도 시험과 릴리프 밸브의 유체유동해석, venting 실험을 통해 현재 개발한 초고압 용적형 펌프의 체절시스템이 작동됨을 확인하였다.

• 수산해양기술연구
• /
• 제35권4호
• /
• pp.428-434
• /
• 1999

Experimental studies on the characteristics of annular jet pump were carried out in this paper. Jet pump can be used widely for the transportation of solid materials, farm produce and fishes. The effects of high pressure chamber on the characteristics of annular jet pump were sought in this paper. Experiments were done for three shapes of high pressure chamber, and for several lengths of the high pressure chamber. Three types of the high pressure chamber's entrances($90^{\circ}$ single inflow, $45^{\circ}$single inflow, and $45^{\circ}$ double inflow) were tested. Water was used for both the primary fluid and secondary fluid. The results obtained in this study are as follows; $45^{\circ}$double inflow type is the most effective among the tested three types of the high pressure chamber's entrances. The efficiency of jet pump with 400mm of high pressure chamber length is the highest among the chamber lengths tested in this study, thus indicating appropriate chamber length is required to get an efficient.

• 드라이브 ㆍ 컨트롤
• /
• 제11권2호
• /
• pp.1-8
• /
• 2014

In this study, the authors carried out experiments and numerical simulations in order to clarify the pressure pulsation characteristics in multiple-delivery rotating-cam and stationary-cylinder type radial piston pumps. Also, a tee filter was applied to the pump in order to mitigate the pressure pulsation. Through the experiments and simulations, it was known that pressure pulsation with a magnitude higher than 40% of the mean load pressure could occur in the pump used in the experiments. Moreover, it was confirmed that a tee filter designed in this study could effectively mitigate the pressure pulsation.