• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.4
• /
• pp.1-7
• /
• 2010

Large quantity of bending deformation as well as irregular rotating torque fluctuation are the main struggles of the balance shaft module during a high speed rotation. Since two issues are much sensitive to the location of both supporting bearing and unbalance mass at a balance shaft, it is recommended to construct a design strategy on balance shaft at the early stage so as to save developing time and effort before approaches to the detailed design process. In this paper, an optimal design formulation is proposed to minimize the elastic strain energy due to bending as well as the kinematic energy of polar moment of inertia in rotation. Case studies of optimal design are conducted for different mass ratio as well as linear combination of objective function and its consequence reveals that global optimum of balance shaft model is existed over possible design conditions. Simulation shows that best locations of both supporting bearing and unbalance are globally 20% and 80%, respectively, over total length of a balance shaft.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.488-493
• /
• 2005

In gun stabilization systems, the torque comes from the unbalance mass of gun and the base acceleration is an important source of disturbance which degrades stabilization performance. Fatigue of gear train is another important factor affecting structural safety problems. In this paper, a feedback control gain is designed by optimal control weighting to difference between motor and gun velocity, and a feedforward controller using FXLMS algorithm is adopted to investigate those problems. Experimental results show that the feedforward compensator based on FXLMS can reduce the disturbance effects. The directional convergence property according to initial conditions of the FXLMS is also shown through experiments.

• The Journal of the Acoustical Society of Korea
• /
• v.15 no.4E
• /
• pp.37-44
• /
• 1996

To get accurate vibration analysis of rotor-bearing systems, finite element models of high speed rotating shaft, unbalance disk, and fluid film journal bearing are developed. The study includes the effects of rotary inertia, gyroscopic moment, damping, shear deformation, and axial torque in the same model. It does not include the axial force effect, but the extension is straighforward. The finite elements developed can be used in the analysis design of any type of multiple rotor bearing system. To show the accuracy of the models, numerical examples are demonstrated.

• Tribology and Lubricants
• /
• v.12 no.2
• /
• pp.8-19
• /
• 1996

Scroll compressor using a slide bushing type radial compliant crank mechanism is modelled, and it's dynamic behaviour characteristics are analyzed. Sealing forces generated in the flank surfaces of the orbiting scroll depending on the distance, e, from slide bushing center to crank pin center are calculated. From the stable condition of orbiting scroll for the moment equilibrium in tangential direction, the range of e is determined as 0$r_o$. Transient response of a crankshaft supported by two journal bearings is investigated, considering applied load, moment, and unbalance force by eccentric mass. As a result, conical whirl mode with circular orbits are obtained. The characteristics of journal orbits and frictional losses are calculated with a variation of viscosity and bearing clearance.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.17 no.5 s.122
• /
• pp.415-426
• /
• 2007

In a link motion punch press, numerous links are interconnected and each link executes a constrained motion at high speed. As a consequence, dynamic unbalance force and moment are transmitted to the main frame of the press, which results in unwanted vibration. This degrades productivity and precise stamping work of the press. This paper presents an effective method for reducing dynamic unbalance in a link motion punch press based upon kinematic and dynamic analyses. Firstly, the kinematic analysis is carried out in order to understand the fundamental characteristics of the link motion mechanism. Then design variable approach is presented in order to automate the model setup for the mechanism whenever design changes are necessary. To obtain the inertia properties of the links such as mass, mass moment of inertia, and the center of mass, 3-dimensional CAD software was utilized. Dynamic simulations were carried out for various combinations of design changes on some links having significant influences on kinematic and dynamic behavior of the mechanism.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.615-620
• /
• 2005

Vibration in Engine module could be reduced by introducing a balance shaft module which has one or more unbalanced rotors. The unbalanced rotor is unbalanced in one direction that act as a opposite direction of the inertia force or moment triggered by engine component so that the largest order factor in vibration is efficiently decreased The ability of balance shaft to reduce the order element of engine component is investigated by a vehicle testing that is focused on comparing the vibration with balance shaft to that of without balance shaft. One of the commonly adapted balance shaft is tested by modal scheme for indemnifying the dynamic characteristics and an, the modal information is used for a clue to design the balance shaft module. The essential equation deriving the design parameters of unbalanced rotor is also presented for two cases, 3 in-ling and 4 in-ling cylinder model. Finally, the overall design process is explained with flow chart.

• Journal of Institute of Control, Robotics and Systems
• /
• v.10 no.9
• /
• pp.840-846
• /
• 2004

In this study, the performance of a heavy load pointing system has been investigated. The PI controller are being widely used in industrial application because of simple, cheap, and excellent performance. However, the requirement for control precision becomes higher and higher, as well as the plants becomes more and more complex. In order to achieve the satisfied control performance, we have to consider the affection of nonlinear factor contained in plant. In this paper, the neural-PI control law have been evaluated. The proposed controller is compared with the existing controllers through simulations, and the results show that the pointing accuracy of the proposed control system is improved against the disturbance induced by vehicle running on the bump course.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.5
• /
• pp.55-63
• /
• 2004

This paper presents neural network based controller using the feedback error loaming technique for a heavy load pointing system. Also the mathematical model was developed to analyze heavy load pointing system. The control scheme consists of a feedforward neural network controller and a fixed-gain feedback controller. This neural network controller is trained so as to make the output of the feedback controller zero. The proposed controller is compared with the conventional PI controller through simulations, and the results show that the pointing accuracy of the proposed control system are improved against the disturbance induced by vehicle running on the bump course.

• Journal of the Korea Convergence Society
• /
• v.13 no.4
• /
• pp.307-313
• /
• 2022

The importance of engine vibration reduction is increasing as the vehicle interior noise becomes more serious due to higher output and lighten weight trends. Recently, the balance shaft attachment has been proposed as a representative method for the engine vibration reduction. The balance shaft is a device that cancels the vibrations generated in the reciprocating motion of the piston and the conrod by using an arbitrary eccentric mass, and can improve fuel efficiency and ride comfort at the same time. This paper proposes the unbalance amount and shape of the balance shaft to induce and offset the inertia force generated by the engine structure. The proposed two-shaped balance shaft was implemented as an ADAMS multi-body dynamics model, and the reduction of the inertial force in the actual behavior was confirmed through dynamic simulation.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.4
• /
• pp.344-351
• /
• 2004

Tilling pad journal bearings have been widely used to support the rotors of the high rotating machinery such as steam and gas turbines owing to their inherent dynamic stability characteristics. However, serious bearing problems such as fatigue damage in the upper unloaded pad, the break of locking pins and the wear of pinholes etc. by pad fluttering are frequently taken place in the actual steam turbines. The purpose of this paper is to investigate the mechanism of pad fluttering and to suggest the useful design guideline(application of preload, m) for the purpose of preventing bearing problems by pad fluttering in a tilting pad journal bearing. It is estimated that upper pad is easy to flutter because the film shape of the upper pad is diverged by moment acting on pivot point. This paper suggests that effective preload range(m $\geq$ 0.5) in order to be statically loaded pad under all operating conditions. Also, design modified bearing is suggested for the adjustment in actual steam turbines. And bearing and rotor dynamic analysis are performed to identify bearing characteristics and to verify the reliability of rotor-bearing system.