• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1383-1389
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• 2011

Gerotor-type volumetric displacement pumps are suitable for oil or water hydraulics. For this reason, many researchers have studied this topic. Gerotor pumps have been widely used in various fields. In this study, we designed a rotor profile based on an envelope of a family of curves. An analytic method for determining the volumetric displacement of the gerotor pump is verified by comparing a result obtained using CAD technology and an experimental result. Throughout the experiment, the flow rate performance was verified. In addition, we describe the design and volumetric displacement characteristics of the gerotor pump.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.891-896
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• 2010

A gerotor is used in power-steering units (PSUs) as well as in hydraulic motors or pumps. The inner rotor is developed on the basis of the shape of the outer rotor tooth, which normally has one arc. The method of generating inner rotor on the basis of a generalized shape of outer rotor is analyzed with a view to improve PSU characteristics. An arc-shaped outer rotor with two curvatures was used in the analysis; design parameters such as the shape and curvature of the inner rotor, the flow rate of the gerotor, the position of contact point, and slip velocity are calculated, and these results are shown. This analysis enables us to develop a new design of compact PSUs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1237-1244
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• 2015

A gerotor can be manufactured in a miniature size because it has a high discharge per cycle and a simple structure. Gerotors are widely used for the lubrication oil of an engine and as the hydraulic source of an automatic transmission. Recently, improvements in fuel efficiency and noise reduction have come to the fore in the automobile industry, and it has been necessary for better fuel efficiency to continuously improve the flow rate and noise of internal gear pumps through the optimal design of the gerotor and port shape. In this study, gerotors were generated based on the equations derived for a lobe shape with multiple profiles (ellipse 1-elliptical involute-ellipse 2). The ranges of the design parameters were considered to prevent a cusp and loop. In addition, the optimal lobe shape was obtained by determining the influence of the lobe shape on the performances (flow rate, irregularity, etc.), according to the values of the design parameters.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.3
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• pp.241-250
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• 2011

The new gerotor developed in this paper has an inner rotor in which a circular arc is inserted between the hypocycloid and epicycloid curves, whereas the outer rotor is designed using the simulation results for the rotor and a modification method. The new gerotor has no cusps and loops and no limit on the eccentricity. We increase the average flow rate by adding a new design parameter, $\gamma$, which is the inclined angle of the inner rotor at the intersection of the hypocycloid and the circular arc. A calculation method to calculate the chamber area is also developed. This method can also be used to calculate the flow rate and flow rate irregularity when the contact points are unknown. The control of eccentricity and $\gamma$ is expected to lead to an efficient rotor.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.119-126
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• 2006

Gerotor hydraulic motor is widely used in hydraulic systems due to its low speed, high torque output and compactness in rotational direct driving of a heavy weight. Gerotor is a Planar mechanism consisted of a pair of rotor and circular teeth of stator assembly which forms a closed space, so called a chamber. The motion of rotor relative to the circular tooth is produced by the pressure difference of hydraulic operating fluid between the adjacent chamber. As all active contact points of rotor and circular teeth are subjected to very high sliding friction, a reduction in the performance of the gerotor hydraulic motor can not be avoided. Therefore, the core design parameters of gerotor profile used in hydraulic motors is to minimize a friction force by high contact stresses. The analytical design method of gerotor profile, based on envelope of a family of curves, is proposed. In this study, the influence of the tip clearances on three critical contact points between rotor and circular teeth of stator assembly has been explored by experimental data in this paper. At the same time a improvement method to reduce the friction force is proposed and the tip clearances on three critical points for getting an optimum gerotor profile are also analyzed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.4
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• pp.406-414
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• 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.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.3
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• pp.43-49
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• 2001

When designing a gerotor, designers determine basic dimensions of a gerotor with transmitted power considering strength, interference and so. on. But, designers can not easily obtain the tooth profile generated by dimensions as well as the geometry bob for cutting the tooth profile. In order to resolve these problems, an automatic design sys-tem creating not only the solid model of a gerotor but also that of the generating hob using the design parameters of dimen-sions is developed. Through the developed system, designers can improve the efficiency of design and satisfy the variable requirements of design as well. In this research, the three-dimensional solid models for gerotors are generated considering the design parameters. Besides, those for generating hob regarding the design parameters of hob is created automatically.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.2
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• pp.8-16
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• 2011

It is hard and complicated to analytically derive the volumetric-displacement formula of a gerotor pump/motor. Analytical formulas for calculating the volumetric-displacement are derived in this work, which is relatively easy and based upon vane lengths. The vane lengths mean the distances from axis of inner rotor or outer rotor to contact points between inner and outer rotors. Two kinds of formula were studied for two different kinematic motions of rotors. The first one is the case that outer rotor is fixed in space and inner rotor is in mixed motion of planetary revolution and rotation with respect to the spinning axis. And the second is the case that both inner and outer rotors simultaneously rotate. The proposed formula is verified through comparison with volumetric-displacement obtained from numerical CAD calculation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.1
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• pp.82-88
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• 2009

A disadvantage in the design of gerotor pump is a lack of parts that can be adjusted to compensate for wear in the rotor set, and as a consequence, it causes a sharp reduction of efficiency. In this paper, an attempt has been made to reduce the wear rate between the rotors of a gerotor pump. To do this, floating genetic algorithm (FGA) is used as an optimization technique for minimizing the wear rate proportional factor (WRPF). The result shows that the wear rate can be reduced considerably, e.g. approximately 8% in this paper, throughout the optimization using FGA.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.10 s.253
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• pp.1019-1025
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• 2006

Numerical simulations were conducted on the gerotor type oil pump. Three oil pump models having different port and groove shape were considered. Firstly, two original models (baseline & variant.1 model) were simulated in order to validate the accuracy of the simulation results and to better understand the flow characteristics in the pump. It was found that the cavitation phenomenon as well as the teeth tip leakage is most important parameter on the pump performance. Based on the simulation results of the original models, final model (variant.2 model) which has improved port shape and pressure relief valve is suggested to enhance pump performance and to reduce driving torque. The volumetric efficiency and the hydraulic torque of the Variant.2 model is improved 4% and reduced 6.1% each at 2000RPM in experiment.