Hyo Seo Kwak

Design and CFD analysis of gerotor with multiple profiles (ellipse–involute–ellipse type and 3-ellipses type) using rotation and translation algorithm

Gerotor is a key component used in internal gear pumps of vehicles, and as the technology of sintering process is highly advanced, the gerotor has advantages for manufacturing complex profiles and obtaining durability and minimization. But internal gear pumps have been continuously required to improve flow rate and noise for fuel efficiency. The existing gerotors with multiple profiles have been designed by only translation algorithm, which is limited to improve the performances. In this study, a new automated design and multiple calculation programs using rotation and translation algorithm were developed for improving the performances of multiple profiles, and two types of combined multiple profiles (ellipse 1-involute-ellipse 2 type and 3-ellipses type) were generated. The performances (flow rate, irregularity, specific sliding and pressure angle) of the profiles were calculated by using theoretical analysis, and optimal designs of the two types were carried out on the basis of analysis results. Also, internal flow characteristics in the optimized gerotor generated were analyzed by using commercial CFD (computational fluid dynamics) code, ANSYS-CFX.

Performance Improvement of Oil Pump by Design of Gerotor (Combined Profile - Two Ellipses) and Port

A gerotor is suitable for miniature manufacturing because it has high discharge per 1 cycle and a simple structure, while also being widely used for lubrication oil of engines and as a hydraulic source of automatic transmission. In the automobile industry, improvements in fuel efficiency and noise reduction have recently come to the fore. It has also been necessary to continuously improve the flow rate and noise of internal gear pumps for better fuel efficiency through optimal gerotor and port shape design. In this study, to develop an optimal gerotor with a new lobe shape, 2-ellipses-combined, the equation of the lobe shape was derived, and CFD analysis results were compared for 2-ellipses with those of the previous gerotors (3-ellipses and ellipse1-involute-ellipse2). A performance test for the oil pump with the optimal rotor (2-ellipses) was carried out and showed good agreement with the results obtained from CFD analysis.

Optimal Design of Gerotor (Ellipse1-Elliptical Involute-Ellipse2 Combined Lobe Shape) for Improving Fuel Efficiency and Reducing Noise

A gerotor is suitable for miniature manufacturing because it has a high discharge per cycle and a simple structure, while also being widely used as lubrication oil of engines and the hydraulic source of automatic transmission. In the automobile industry, it has been necessary to continuously improve the flow rate and noise of internal gear pumps for better fuel efficiency through optimal gerotor design. In this study, to obtain an optimal gerotor with an ellipse-elliptical involute-ellipse combined lobe shape, an automatic program was developed for calculating performance parameters and drawing a gerotor profile. An oil pump was assembled with the optimal gerotor together with the port used at the actual field and CFD analysis was performed on this assembly using Ansys-CFX. A performance test for the oil pump was carried out and showed good agreement with the results obtained from the theoretical analysis and the CFD analysis.

Optimal Design of Gerotor with Combined Lobe Profiles (Ellipse 1-Elliptical Involute-Ellipse 2)

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. † Corresponding Author, chulki@pusan.ac.kr C 2015 The Korean Society of Mechanical Engineers 곽효서 · 이승환 · 김 철 1238 기존 제로터 관련 연구에서는 Colburne가 외부로 터 로브 형상이 원인 경우 로터 설계시 첨점 및 루 프가 발생하지 않기 위한 최대 반경 공식을 유도하 였고 내부로터의 곡률반경, 외부로터 형상 및 치높 이 등과 이론적 유량 및 유량맥동과의 상관관계를 규명하였다. Saegusa 등은 로터 팁간극의 계산 및 첨점 형상 개선을 통해 유량 측면에서 보다 효율적 인 트로코이드 로터를 설계하였다. Beard 등은 하이 포 트로코이드 및 에피 트로코이드 로터를 설계하고 이론적 유량, 작동챔버 이동거리 및 체적비 등을 비 교하였다. Fabiani 등은 내부로터 회전각에 따른 챔 버면적 변화율을 적분하여 유량 계산 후, 이에 대한 시뮬레이션 및 실험을 수행하였다. Mimmi 등은 한 계곡선을 이용하여 로터 설계 시 언더컷을 방지할 수 있는 방법을 개발하였다. Demengo 등은 간섭 및 마모방지를 위한 사이클로이드 로터를 설계하고 접 촉응력 계산 프로그램을 개발하였다. Lee은 제로터 의 내부누유 방지 및 가공편의를 위해 내부로터 형 상을 원호조합곡선으로 보간하는 방법을 개발하였으 며 Ye 등은 외부로터 로브 형상이 원인 경우 첨점 및 루프 발생 방지를 위한 최대 반경 공식을 보다 간단한 방법으로 유도하였다. Chang 등은 외부로터 로브형상이 원인 경우의 로터 설계 및 이의 성능인 자 계산을 위한 자동화 프로그램을 개발하였으며 Hsieh 등은 트리코이드 곡선을 이용한 로터를 설 계하고 간섭, 언더컷 방지 및 체적효율 향상을 위한 기법을 개발하였다. Sasaki 등은 내부로터에 인벌 루트 곡선을 삽입하여 기존의 개발된 Parachoid rotor 보다 효율이 우수한 Megafloid rotor를 개발하였으며, Kim 등은 외부로터 로브형상이 타원 및 인벌루트 등의 다양한 곡선으로 조합된 로터를 설계하고 이의 유량 및 유량맥동 계산을 위한 자동화 프로그램을 개발하였다. 위의 연구 결과를 기반로 하여 본 연구에서는 기존의 치형 설계에 일반적으로 사용되어 왔던 원 형상으로부터 얻어지는 인벌루트와는 달리, 타원 으로부터 얻어지는 인벌루트(타원형 인벌루트, elliptical involute)를 이용하여 두 개의 타원과 그 사이에 타원형 인벌루트가 조합된(타원 1-타원형 인벌루트-타원 2) 로브 형상을 가진 외부로브에 대한 치형의 기구학적 관계식을 유도하여 내부로 브 형상을 설계하였다. 또한 창출된 치형에 대하 여 첨점 및 루프가 발생하지 않는 설계인자 범위 를 결정하였고 설계인자의 크기 변화가 치형의 형 상 및 성능인자(유량, 유량맥동)에 미치는 영향을 파악하며 최적의 치형을 도출하였다. 2. 이론적 해석 2.1 타원 1-타원형 인벌루트-타원 2 조합형상을 가지는 치형 설계 2.1.1 타원 1-타원형 인벌루트-타원 2 조합형상 함수 기존의 치형 설계에 적용되는 기초 원에서 도출 되는 인벌루트와는 달리, Fig. 1 과 같이 타원에서 얻어지는 인벌루트(타원형 인벌루트)를 치형 설계 에 새롭게 적용하였다. 여기서 타원형 인벌루트의 형상함수는 식 (1)~식 (2)이다.         + ⋅ ⋅ − =         + ⋅ ⋅ + =

A Study on Structural Safety of the Boom Hoisting Cylinder of a Coal Handling Machine

A coal handling machine is a type of equipment used for loading coal, the main material in a steam power plant, along a conveyer belt from a ship, and is placed after the driving chain bucket. However, studies on the boom hoisting cylinder, which is a hydraulic system used to control the angle of the boom based on loading location, indicate that domestic models are insufficient, and are thereby often substituted with a foreign product. In this study, a technique for analyzing the contact pressure in a thick-walled cylinder was established by comparing the contact pressure, which is calculated theoretically based on the results obtained from FEM simulation, and by checking whether the working oil is leaking from the boom hoisting cylinder using a v-seal. In addition, the driving motion was simulated according to the strokes of the cylinder, and the structural stability was verified under the maximum output conditions.

Development of an Advanced Oil Deflector Used in Thermoelectric Power Plant

Oil deflector prevents oil leakage that occurs in thermoelectric power plant at operating lubricant facilities. Vibration of rotating rotor-induced wear of aluminum tooth in existing oil deflector leads to oil leakage as well as life shortening of the tooth. In this study, an advanced oil deflector was developed for shock absorption and prevention of wear by decreasing clearance (from 0.5 mm to 0.2 mm) between rotor and tooth to minimize oil leakage, and by replacing 2 aluminum teeth in outmost of the oil deflector with hi-performance seal made of engineering plastic. The CFD results were compared between advanced vs. existing oil deflector to determine the amount of oil loss. Structural safety was verified through impact analyses according to the three kinds of engineering plastics, considering cost efficiency, and optimal material of hi-performance seal was chosen.

Progressive Process Design for Delta Sash in Vehicles

Delta sash is an important part of automobile door, which has the functions of supporting and guiding seesaw of car’s window, preventing dust and air from outside. In previous manufacturing process, each part of the delta sash was independently formed by tandem processes, and rubber is bonded to steel by poisonous glue. So, the previous processes, including roll forming process and toxic gases, had low production rate and high failure rate. In this study, progressive process design of the delta sash was proposed in order to increase productivity and high utilization of the materials. And instead of the poisonous glue used for adhesion of rubber in the previous tandem process, embossing and piercing processes were designed in the new guide to help the rubber to adhere well to steel. And the optimal piercing distance was designed to ensure structural safety, and prototypes were manufactured for verifying reliability of the processes.