• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.2
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• pp.247-254
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• 2003

The paper presents the influence of spring dynamics and friction on dynamic responses in a spring-driven cam system. The characteristics of the friction on the camshaft are analyzed using the nonlinear pendulum experiment while the parameters of the friction model are estimated using the optimization technique. The analysis reveals that the friction of the camshaft depends on stick-slip, Stribeck effect and viscous damping. Spring elements are found to have much influence on the dynamic characteristics. Hence, they are modeled as four-degree-of-freedom lumped masses with equivalent springs. The appropriateness of the derived friction model and spring model is verified by its application to a vacuum circuit breaker mechanism of the cam-follower type.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.47-53
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• 2001

Power Circuit Breaker uses a variable-speed cam mechanism actuated by pre-loaded spring force. This paper presents the optimal design procedure for a variable-speed cam mechanism based on the dynamic model of a complete spring-actuated cam system. The optimal cam is compared with an original cam. Simulation results show that the dynamic behaviors of the designed cam are superior to those of the original cam.

• Transactions of the KSME C: Technology and Education
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• v.1 no.1
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• pp.1-6
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• 2013

A SIM card socket is used for a cell phone to fix an USIM card and a push-push mechanism is typically employed in the SIM card socket for a user convenience. A SIM card is inserted with locking when a user pushes the card once and a SIM card is removed with unlocking when a user pushes the card again. A push-push mechanism is operated by a heart-cam structure and a main spring. A cam slider and a cam stick consisting a push-push mechanism may be broken because of the main spring. So, dynamic stress at a cam slider and a cam stick which is generated by a main spring during operating should be analyzed and considered in the push-push mechanism design. In this paper, a flexible multibody model of a push-push mechanism was developed to analyze dynamic stress at a cam slider and a cam stick.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.78-87
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• 1998

A dynamic model of direct-acting OHC valve train system has been used to determine the load conditions in the system. The modified equations for calculating the friction forces between cam and HLA, and at a camshaft bearing have been defined considering the lubrication conditions. Then, to understand the frictional characteristics in the system, a parameter study has been performed. As the results of the analysis, valve spring stiffness and preload have great effects on the friction in the system, but the effects of other parameters are negligible. So, how to design the valve train system with respect to the reduction of friction is to minimize the valve spring stiffness and preload in the limit of satisfying the dynamic constraints.

• Journal of KSNVE
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• v.4 no.1
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• pp.83-88
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• 1994

In many circumstances, it is desired to move a mass from one position to another without inducing and vibration in the mass being moved. Two such problems are considered here : the motion of a mass initiated by another mass, nd the motion of a pendulum initiated by the specified motion of its support. In each case, it is dosired that the system start at rest and come to rest in the second position. A simple strategy for the specified motion is given here. The method is motivated by engine cam-follower design. The force required to move the system in question is determined as well as the maximum value of the force required(and the times at which these forces take place).