Gerotor oil pumps are widely used for the lubrication oil of an engine and the hydraulic source of an automatic transmission. Recently, improvements for the purposes of fuel efficiency and noise reduction have come to the forefront of the automobile industry, and it has become necessary to study the design of gerotors and ports. In this study, an expanded cardioid curve was developed, and an equation for a tooth profile with an expanded cardioid lobe shape has been suggested to reduce pump noise. The design was created using an automatic program; the program generated inner and outer rotor profiles and calculated performance parameters. Also, in order to decrease irregularity, CFD analyses were performed according to groove shapes in the exhaust port. Results showed the noise of the improved oil pump (the suggested gerotor [expanded cardioid] + the proposed port) was 5.44% lower than the existing oil pump (the existing gerotor [2-ellipse] + basic port).

In this paper, we compared the performance of the mechanical inertia and electronic inertia used in the friction coefficient measurement process, as this is the main function of the braking performance tester. The comparative test was carried out 36 times under mechanical inertia and electronic inertia. Stop braking was performed at various braking speeds (120, 160, 200, 220 ㎞/h), and at various contact force conditions (8, 18, 25 kN). We compared the instantaneous coefficient of the friction, the average coefficient of the friction, the braking force, and the braking distance with the mechanical inertia and the electronic inertia, by taking the average of the three tests we performed each for braking velocity and contact force. In addition, the friction coefficient ratio and the energy ratio were calculated. As a result, it was confirmed that the test using the electronic inertia compared to the test using the mechanical inertia appropriately reflects the bearing frictional force and the rotational resistance loss of the tester, and the kinetic energy is consumed as the braking energy without loss.

A paper cup forming machine performs the entire process to produce paper cups. Recently, as the demand for paper cups in various fields increases, the need for rapid and timely paper cup forming also increases. However, the more rapid the manufacturing speed is, the higher the possibility of forming failure. Frequent fault occurrences cause a time-consuming and costly repair process and reduces manufacturing efficiency. Among various fault factors in this research, position deviation of the paper from the original position, which induces a jamming and process stop, was selected and a novel deviation detecting system using multiple photo sensors was suggested. Before operating the position detecting system, the performance of the photo sensors was evaluated with respect to response speed and photo beam precision. A deviation detecting mechanism was designed. The developed deviation detecting system was integrated with the paper cup forming machine and experimented with using base papers. It was conformed that the suggested system could be used to diagnose paper deviation failure.

Recently, technologies related to green cars are gaining attention. A variable valve-timing system (VVT) is widely used in internal-combustion engines to improve fuel efficiency and engine performance by controlling the valve open-close timing. Since conventional hydraulically controlled VVT has problems, such as slow response and low efficiency, an electrically controlled variable valve timing (ECVVT) system was developed as an alternative the conventional VVT. This paper presents a performance test rig for an ECVVT system using servo motors. The performance test rig consists of an ECVVT module with a cycloid reducer, an engine cylinder block, a driving part, and a motion controller. A small servo motor drives the ECVVT module through the cycloid gear, while a large servo motor drives the camshafts by means of a timing belt. We carried out simulations using a mathematical model of the ECVVT module, cam shaft, valve, and motion control. We then built a performance test rig for the ECVVT system, and did experiment of cam phase variations of the ECVVT system to confirm its performance.