• Korean Journal of Computational Design and Engineering
• /
• v.17 no.5
• /
• pp.312-323
• /
• 2012

Planetary gearing is a gear system consisting of one or more planet gears, revolving about a sun gear. While the planetary gear system has many advantages- for example, high power density, large reduction in a small volume, multiple kinematic combinations, pure torsional reactions, and coaxial shafting, it has not been widely used because of its high bearing loads, inaccessibility, and design complexity. It is also necessary to shift several pairs of gear profiles at a same time. Therefore, designing profile shifted planetary gear system is a difficult and know-how dependent job. This study provides a practical solution to design a profile shifted gear system by the procedural design scheme, and proposes a bearing integrated structure of the dual stage profile shifted gear system with a robust output end. A dual stage profile shifted gear system with the bearing integrated structure is manufactured by the proposed design scheme in this study. This gear system is verified that it is good enough to commercialize, because it has high performance with high gear ratio and robust output end against axial and radial directional runouts in a small space.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.10
• /
• pp.36-43
• /
• 2020

A marine turning gear is the main auxiliary machine that enables the disassembly of and maintenance on the main engines. In this study, a marine turning gear based on a helical planetary reducer was developed through analysis of a marine turning gear based on a spur planetary reducer. Nonlinear numerical analysis was performed to determine the ideal contact ratio between the sun gear and the idle gear. Based on this, the surface durability, tooth bending strength, and contact ratio were calculated. In addition, the helix direction was selected to utilize the existing bearings. Gears were manufactured based on the helical gear design values, and the turning gear was evaluated using the FTA standards of MAN Co. Ltd. As a result, a lifetime of 3,000 to 5,000 hours was verified, the maximum torque measured was 105kNm, and the efficiency was measured to be 87.4%.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.5
• /
• pp.537-543
• /
• 2012

In this study, we experimentally investigate a noise mechanism related to the machining accuracy of the reducer in the driving state. We fabricate a planetary reducer and four types of gears for use in the planetary reducer. We use signal analysis to determine the noise and vibration of the reducer at different motor speeds; the motor speed is increased from 0 rpm to the maximum speed in a stepwise manner. In addition, we obtain the sound level by using a sound level meter. The machining accuracy of gears is evaluated by public organizations, Korea Testing Laboratory (KTL), on the basis of the Japanese Industrial Standard (JIS). We analyze and compare the results with the noise and vibration of the reducer.

• Journal of the Korean Institute of Gas
• /
• v.26 no.2
• /
• pp.9-13
• /
• 2022

Electric wheelchairs, the output from the motor is mainly applied to a speed reducer using a power transmission device such as a belt or a chain. However, although a speed reducer using a belt or chain is a simple device, it occupies a lot of space and has a space limitation, so it is not suitable for an electric wheelchair driving part. However, since the speed reducer of the planetary gear type is decelerated on the same axis, the volume can be reduced, so the space constraint is less than that of the belt or chain type reducer. Therefore, in this study, a driving part that can obtain great propulsion with a speed reducer using a planetary gear type was developed through a study on the driving part of a wheelchair that can be switched between manual and electric. Accordingly, the tooth shape of the planetary gear applied to the reducer was designed using the Kisssoft program. In addition, the drive part was designed to be applicable to the existing wheelchair wheels, and the mechanism was optimized for the manual/electric switching principle and operation principle of the drive part. Based on the research contents, the final design and manufacture of the wheelchair reducer drive unit in the form of a planetary gear having one sun gear, two planetary gears and one ring gear was carried out.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.5
• /
• pp.559-566
• /
• 2016

This study shows a development procedure and results of noise reduction for a new developed FF 8th speed automatic transmission. Based on planetary gear operating frequency analysis using PTA(planetary transmission analysis) program developed in 2012, It is expected that gear noise of the rear planetary gear set could be recognized easily in the concept design stage. Therefore, pRMC (planetary run many cases) analysis program that is developed in 2012 was applied to minimize the planetary gear noise level and noise distributions versus torque. To minimize noises coming from oil pump and final gears of a new transmission, several changes were applied, such as changing the clearance of double angular ball bearing, the oil pump rotor tooth number from 9 to 11 and the oil pump type from parachoid to megafloid and so on. Besides, stiffness values of the transmission case and the mount bracket were measured and reinforced properly. Finally, The total noise of the new FF 8th speed automatic transmission was developed successfully. Furthermore, E.O.L. testers also have been adapted to control the noise quality of automatic transmission assembly in the manufacturing factory. This paper could provide practical solutions to the automatic transmission NVH problems.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1775-1780
• /
• 2003

A hybrid finite element analysis was used to analyze the influence of ring gear rim thickness and spline number on the static properties of an epicyclic gear system with manufacturing errors. Both of these parameters affected the bearing force and critical stress. The effect of changes in the rim thickness on the load sharing between the gears depended on the type of manufacturing error. Ring flexibility improved the load sharing between planetary gears only in systems with planet tooth thickness or planet tangential errors; for other types of error, ring flexibility worsened the load sharing. To improve load sharing, rim thickness and spline number should be controlled within a specific range. The effect of the ring gear boundary condition was more apparent in a system with errors than in a normal system.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.15 no.5
• /
• pp.66-72
• /
• 2016

Gearboxes are mechanical components that transmit power by adjusting input and output speed and torque. Their design requirements include small size, light weight, and long lifespan. We have investigated the effects of carrier pinhole position error on the load sharing and load distribution characteristics of a planetary gear set with four planet gears. The simulation model for a simple planetary gear set was developed and verified by comparing analytical results with a putative model. Then, we derived the load sharing and load distribution characteristics under various pinhole position error conditions using the prototypical simulation model. The results showed that the mesh load factor and face load factor increased with the pinhole position error, which then influenced the safety factor for tooth bending strength and surface durability.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.5
• /
• pp.1-6
• /
• 2017

Gear tooth micro-geometry modifications include the intentional removal of material from the gear teeth flanks, so that the shape is no longer a perfect involute. If the gear shapes are perfect, then the gear tooth meshing is better, therefore the gears will transmit input torque in a more efficient manner without the generation of high frequency engine fluctuation noise. In this paper, we study tooth micro-geometry optimization of rear gear set in 2 speed planetary gear reducers. Analysis revealed problems which are need of modification. Based on the results, tooth micro-geometry was used to deal with load distributions on the rear gear set.

• Journal of the Korean Institute of Gas
• /
• v.26 no.2
• /
• pp.21-26
• /
• 2022

Since the four-wheel drive transmits the driving force to all four wheels, the traction with the road surface increases, thereby increasing the driving force. However, it has the disadvantage of lowering fuel efficiency. Therefore, four-wheel drive is commonly used as a method of converting to optional four-wheel drive when necessary while driving in two-wheel drive. This selective four-wheel drive converts the driving force by mechanically changing the electric signal sent by the driver in the transfer case. In this study, in order to mechanically change the electrical signal, a reducer is applied to the motor to increase the torque to perform the function. Therefore, in this study, a reduction mechanism applicable to the motor inside the transfer case applied to convert the drive is derived, and the reduction ratio applying the planetary gear type is optimized accordingly. And based on the derived reduction ratio, two sets of planetary gears using a ring gear in common were applied to develop a planetary gear tooth type in which the input shaft and output shaft are decelerated in the same phase. Optimization design was carried out.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.263-266
• /
• 2001

The performance of the powertrain can be analyzed using dynamic models including transient characteristics, and the equations of motion can also be derived from the dynamic models of the powertrain. In this study, the shift transient characteristics of the vehicle equipped with Ravigneaux type planetary gears automatic transmission has been investigated.