• Journal of Drive and Control
• /
• v.14 no.1
• /
• pp.1-7
• /
• 2017

The power train of a concrete truck mixer reducer includes differential planetary gears to get a large reduction ratio for operating the mixer drum in a compact structure. These differential planetary gears are a very important part of the mixer reducer where strength problems are the main concern. Gear bending stress, gear compressive stress and scoring failure are the main concerns. Many failures in differential planetary gears are due to the insufficient gear strength and resonance problems caused by major excitation forces such as gear mating failure in the transmission. In the present study, where the excitation frequencies are the gear tooth passing frequencies of the mating gears, a Campbell diagram is used to calculate differential planetary gear critical speeds. Mode shapes and natural frequencies of the differential planetary gears are calculated by CATIA V5. These are used to predict gear resonance failures by comparing the working speed range with the critical speeds due to the gear transmission errors of the differential planetary gears.

• Journal of Advanced Marine Engineering and Technology
• /
• v.36 no.2
• /
• pp.267-275
• /
• 2012

In this study, normal wind load and blast wind load are modeled mathematical. And the periodical torque and bending moments transmitted to the main shaft of wind turbine are investigated. A normal wind model assumed, of which the wind velocity is increased according to the height from ground. The average values and the harmonic terms of the transmitted moments are studied on the wind direction of range $-45^{\circ}{\sim}45^{\circ}$ and the bending moment characteristics are examined, which is regarded as the main source of the misalignment of gear train. In normal wind load case, excitation frequency is 3X (X : Rotor speed). When the wind direction is $+22.5^{\circ}$, the horizontal axis of bending moment occur the 50% of main torque. This result leads to edge contact of gear teeth by shaft elastic deformation. In blast wind load case, excitation frequency are 3X,6X,9X. Additional, in the (+) direction of wind load, relative harmonic percentage is increase.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.5
• /
• pp.514-520
• /
• 2015

The effects of suspension stiffness on the reaction load of the gearbox suspension for a three-point suspension wind turbine drive train were investigated by finite element analysis. The reaction forces of the gearbox suspension appear to increase as the gearbox suspension stiffness increases; however, the main bearing stiffness has a reverse effect on the reaction forces. The influence of the gearbox suspension stiffness is greater than that of the main bearing. Since the suspensions must provide the gearbox with proper support, it is not practical to use soft gearbox suspension for small reaction forces. It is more feasible to use stiff main bearings. As a guideline for the main bearing stiffness in the present study, we propose a relative stiffness of 100-150% of the reference.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1763-1764
• /
• 2008

직류 전동기를 제어하기 위해서는 포텐셜 미터나 엔코더 등의 센서들을 이용하여 직류 전동기 회전자의 위치를 검출하는 것이 필요하다. 산업적인 측면에서 직류 전동기를 이용하는 이유 중 하나는 구동이 간단하고 값이 싸기 때문인데, 상대적으로 고가 장비인 센서들을 이용하는 것이 직류 전동기를 이용한 제품의 가격을 올리는 요인이 된다. 그렇기 때문에 이러한 센서들을 사용하지 않고 피드백 제어가 가능하다면 가격적인 측면에서 큰 이점이 된다. 본 논문에서는 직류전동기의 역기전력에 의해 생성되는 특정한 신호를 이용하여 엔코더의 출력신호와 같은 형태의 신호를 생성하는 회로를 설계하였다. 또한 생성한 출력신호를 이용하여 기어 트레인이 있는 직류 전동기의 위치를 제어하였다.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.3
• /
• pp.278-286
• /
• 2015

The effects of the main bearing stiffness combined with vertical non-torque force on the input load and shaft deflection of a gearbox were investigated for the three-point suspension drive train of a wind turbine. A finite element analysis model for the drive train was studied experimentally, and its applicability to the present study was verified. The results show that, as the main bearing stiffness is increased, the input load of the gearbox decreases, whereas the input shaft deflection increases. The stiffness component for the pitch moment has the largest influence on the gearbox input load. Although the gearbox life increases at a higher main bearing stiffness, the economic efficiency and durability of the entire drive train system should also be considered in the selection of the main bearing stiffness.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.12
• /
• pp.1718-1723
• /
• 2015

The diameter of the rotor of 2MW wind turbine is being developed by a number of companies with more than 80m, reliability and economic efficiency of the wind power generator has been improved. The need for large-scale wind turbine with excellent economy has been attracting attention because the new orders and the location of the wind turbine market has reached a limit. Technology development for enlargement of wind turbine is possible not only the improvement of energy efficiency but also reduce the construction costs per unit capacity. However, mechanical gearboxes used in wind generators have problems of wear, damage, need for lubrication oil and maintenance. Therefore, we want to configure the gearbox of a large-scale wind turbine using a magnetic gear in order to solve these problems of mechanical gearbox.

• Fire Science and Engineering
• /
• v.32 no.1
• /
• pp.57-65
• /
• 2018

In this study, a post-fire safe shutdown analysis (PFSSA) including multiple spurious operation (MSO) treatments for cables was conducted with an imaginary nuclear power plant for training using a deterministic fire analysis code. The imaginary nuclear power plant for the training consisted of a reactor containment building and an auxiliary building, including a total of 22 fire areas. The equipment including valves, pumps, emergency diesel generators, switch gears, motor control centers, and logic controllers were located in each fire area of the imaginary plant. It was assumed that each equipment is connected with two cables and that each cable passes through the fire areas along the cable trays. A database containing the information on the equipment and cables for the imaginary plant was constructed for the fire area analysis. The fire area analysis was performed for several assumed MSO scenarios, equipment logics, and cable logics. A mitigation measure using a three hour rated wrap was applied to the failed cables and cable trays after the fire area analysis.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.15 no.6
• /
• pp.487-497
• /
• 2010

This paper describes the PSIM simulator for the analysis of the series type HEV operation. The traction force of the series type HEV of which engine is electrically coupled with a traction motor is supplied from the traction motor only. The rating of each power train components, such as gear, motor, ESS, ICE/generator, is designed with the Energy-Based Modeling method and the Electrical Peaking Hybrid(ELPH) method. Under driving cycle, the designed series HEV is evaluated with the developed PSIM simulator. A comparison between the conventional braking and the regenerative braking is performed with the average motor input power. And the fuel economy analysis is carried out on the basis of the simulation results.

• Journal of Drive and Control
• /
• v.14 no.4
• /
• pp.71-78
• /
• 2017

The power train of hydro-mechanical continuously variable transmission (HMCVT) for 8-ton class forklift includes hydro-static units, hydraulic multi-wet disc brake & clutches and complex helical & planetary gears. The helical & planetary gears are key components of HMCVT's power train wherein strength problems are the main concerns including gear bending stress, gear compressive stress, and scoring failure. Many failures in power train gears of HMCVT are due to the insufficient gear strength and resonance problems caused by major excitation forces, such as gear transmission error of mating gear fair in the transmission. In this study, wherein excitation frequencies are the gear tooth passing frequencies of the mating gears, a Campbell diagram is used to calculate the power train gears' critical speeds. Mode shapes and natural frequencies of the power train gears are calculated by CATIA V5. These are used to predict resonance failures by comparing the actual working speed range with the critical speeds due to the gear transmission errors of HMCVT's power train gears.

• Journal of the Korean Society for Precision Engineering
• /
• v.33 no.10
• /
• pp.829-835
• /
• 2016

Electro-Mechanical Actuator installed on the aircraft plays a key role in an aircraft's flight control through flight control computer. Reliable prediction of the actuator is important for the aircraft. To estimate the lifetime of a product, it is necessary to test full target life. However, it is very difficult to perform it due to the long life time of actuator but short period of development time with increasing cost. Therefore, accelerated life test has been used to reduce the test time for various reasons such as reducing product's development cycle and cost. In this paper, to predict the lifetime of the actuator, we analyzed the flight profile of aircraft and adapted the method of accelerated life test in order to accelerate failure modes that might occur under user conditions. We also set up an endurance test equipment for validating the demanded lifetime of an actuator and performed accelerated life test.