Gerotor pump technology is being increasingly employed in innovative application fields, such as engines and as the hydraulic source of automatic transmissions. The most important issues in the automobile industry in recent years are improvement of fuel efficiency and noise reduction, so the existing studies relating to design of the gerotor profiles and the port in gerotor oil pumps have been conducted to ensure high flow rates and low irregularity. This study proposes a new gerotor lobe shape with 2-expanded cardioids to reduce the noise of the oil pump used in the automatic transmissions of automobiles. Theoretical equations to generate the tooth profile with 2-expanded cardioids was established, and then the gerotor profile to reduce noise was proposed using an automatic program. A design method for generation of a port shape suitable for the proposed gerotor was introduced, and performance tests (2000 rpm~3000 rpm) of the new oil pump with the suggested gerotor and port shape were implemented. The test results showed that the flow rate was improved by 7.3%~1.5% and the noise was reduced by 2.8 dB~4.8dB compared to those of the existing oil pump, so it was demonstrated that the design methods for the gerotor with 2-expanded cardioids and the port shape were validated. It is expected that the new lobe shape with 2-expanded cardioids and the port shape design method could be adopted in various fields, and will contribute to improving the performance of oil pumps.

In combined cycle power plants (CCPPs), the bypass butterfly valve is a key component to facilitate regulation of exhaust gas energy available at the turbine and to not produce too much boost pressure. The conventional damper valve causes leakage, back flow into the turbine, and damage of the blade, and the existing dual-layered seal with polytetrafluoroethylene (PTFE) and metal should be frequently replaced owing to its low durability and deterioration of mechanical properties under a high temperature. This study devised a triple offset butterfly valve with a new type of seal by alternatively laminating stainless steel and graphite to improve valve performance at the high temperature (350 °C). The slope angles of the seal contact surface to prevent friction were calculated using the mathematical models of the triple offset. Thermal-structure coupled analyses by varying the number of graphite and thickness were conducted, and the seven-layer model with the graphite thickness of 0.8 mm, which shows airtightness and smooth operation, was chosen. The contact stresses behaviors of the graphite at 350 °C and at −196 °C were investigated, and it was found that the graphite is in charge of improving driving performance of the disc at the high temperature and sealing performance at the cryogenic temperature. The performance tests and the field tests of the suggested model verified its performance at the working temperature.

Type II storage vessel, which consists of a metallic liner hoop wrapped with a carbon fiber-resin composite to work at high pressure, has been widely adopted as the fuel container for compressed natural gas (CNG) vehicles. The general vessel, manufactured by welding enclosures to an open-end cylinder, shows uniform thickness throughout the whole liner, while the high pressure vessel, fabricated by the deep drawing and ironing (D.D.I) and spinning processes, has the integral junction part of cylinder with increased end thickness along the meridian direction. This study established a design method for improvement of failure resistance and inner capacity of the seamless CNG pressure vessel (Type II) through finite element analysis with consideration of thickness variation. Autofrettage pressure is used to enhance fracture performance and fatigue life of the vessel, and variations of stress behaviors in the liner and composite were analyzed during the autofrettage process. The influence of the composite on generation of compressive residual stress was investigated. In order to verify advantages of the D. D. I. and the spinning processes for structural safety at the end closure, the stress distribution considering thickness variation was compared with that with uniform thickness, and the maximum inner capacity objective satisfying structural reliability was obtained. The inner capacity of the proposed model with the ratio of major axis to minor axis, 2.2, was expanded by 4.5. Theoretical equivalent stresses were compared with those from the simulations, and the technique of FEM was verified.